IRLF 


B    M    ID  (a 


ELEMENTS 
PHVsfoLOGY 


COLEMAN 


UNIVERSITY  OF  CALIFORNIA 


DEPARTMENT  OF  EDUCATION 


GIFT   OF  THE   PUBLISHER 
No.  Received  / )  Of 


C  j~£0- 


THE   ELEMENTS    OF    PHYSIOLOGY 


THE    ELEMENTS    OF 

PHYSIOLOGY 


FOR    SCHOOLS 


BY 


WALTER   MOORE    COLEMAN,  A.B. 

FELLOW   OF  THE   PHYSICAL   SOCIETY   OF  LONDON;    AUTHOR    OF   "  SOCRATIC 

LESSONS    IN    SCIENCE   FOR   TEACHERS,"    "  CONTRACTILITY    OF  A 

MUSCLE  CELL,"   "ELEMENTARY  PHYSICS,"   ETC. 


WITH  248  ILLUSTRATIONS,  INCLUDING  COLORED 
PLATES  AND  MANIKIN 


gorfe 
THE    MACMILLAN    COMPANY 

LONDON  :  MACMILLAN  &  CO.,   LTD. 
1904 

All  rights  reserved 


COLEMAN'S   PHYSIOLOGICAL  SERIES. 


PHYSIOLOGY  FOR  BEGINNERS.  For  Intermediate 
and  Lower  Grammar  Grades.  Illustrated  with  many 
half-tone  engravings  and  figures.  181  pages. 

THE  ELEMENTS  OF  PHYSIOLOGY.  For  an  ex- 
tended course  in  Graded  Schools  and  Rural  Schools, 
and  for  a  review  course  in  High  Schools,  Academies, 
and  Normal  Schools.  With  248  illustrations,  includ- 
ing colored  plates  and  manikin,  xi  -f  358  pages. 


COPYRIGHT,  1903, 
BY  THE  MACMILLAN   COMPANY. 


Set  up,  electrotyped,  and  published  August,  1903.     Reprinted 
November,  1903;  February,  1904;  August,  1904. 


Norwood  Press 

J,  S.  Gushing  &  Co.  —  Berwick  &  Smith  Co. 
Mass.,  U.S. A 


TO    THE    TEACHER 

THE  human  body  is  made  of  cells  and  its  life  consists 
in  the  activities  of  the  cells.  Physiology  is  the  study  of 
the  cells  and  tissues  in  their  related  activities.  Yet  the 
usual  school  physiology  neglects  the  functions  of  the 
cells  and  tissues  and  studies  organs  almost  as  isolated 
things,  rather  than  as  component  parts  of  the  bodily 
structure.  The  well  organized  science  of  physiology  is 
thus  slighted  and  the  result  is  an  unnecessary  waste  of 
time.  The  experience  of  the  author  with  young  students 
has  convinced  him  that  elementary  facts  in  the  science  are 
not  so  difficult  of  comprehension  when  given  in  their  real 
relations  as  when  given  as  isolated  facts. 

But  due  regard  solely  for  logical  order  would  require  that 
the  pupil  be  inducted  at  once  into  the  study  of  protoplasm 
and  cells,  which  are  to  him  mysterious  subjects.  The 
interest  naturally  excited  by  beginning  a  new  study  would 
be  killed  before  he  reached  things  that  he  knows  some- 
thing about.  The  science  of  teaching  requires  that  we 
begin  with  things  well  known  to  the  pupils  and  proceed 
through  the  known  to  the  unknown.  Evidently  no  subject 
is  so  well  adapted  for  the  starting  point  as  the  skin.  The 
surface  of  the  body  is  familiar ;  personal  appearance  is  a 
subject  of  interest  to  young  people  ;  for  these  reasons  the 
skin  is  a  suitable  subject  for  introducing  the  stucty.  Cell- 
life  being  an  unknown  subject,  it  is  treated  at  first  in  the 
simplest  and  most  elementary  manner,  but  constant  return 
to  it  is  made  in  the  discussions  of  each  organ  and  func- 
tion. As  the  nerves  are  intimately  related  to  every 
organ,  some  authors  attempt  an  exhaustive  treatment  of 


VI  TO    THE    TEACHER 

the  nervous  system  in  the  first  chapters,  but  this  method 
has  the  insuperable  objection  of  treating  the  most  difficult 
subject  first.  Recent  authors  have  relegated  the  simple  sub- 
ject of  the  skeleton  to  the  last  as  it  is  supposed  to  be  the 
least  interesting  and  of  least  importance  hygienically.  In 
this  book  it  is  introduced  among  the  first  chapters,  because 
a  knowledge  of  the  skeleton  furnishes  a  scheme  by  refer- 
ence to  which  all  the  organs  of  the  body  may  be  located  as 
studied,  thus  promoting  a  definite  knowledge  of  anatomy, 
without  which  foundation  physiology  cannot  be  learned. 

The  teacher  will  notice  the  incorporation  of  frequent 
exercises,  thought  lessons,  applications,  and  practical  ques- 
tions as  a  training  for  the  reasoning  faculty.  These  were 
tested  by  a  number  of  teachers  with  hundreds  of  pupils 
before  being  set  in  type.  Where  they  may  seem  ambig- 
uous, it  is  usually  because  more  definite  statements  would 
be  equivalent  to  giving  the  pupil  the  answers. 

That  the  power  of  observation  may  be  cultivated,  fre- 
quent observations  of  the  pupil  on  his  own  body  and  on  the 
life  of  the  community  are  called  for,  and  after  the  more  im- 
portant figures  and  plates  quizzes  are  inserted  which  can 
be  answered  only  by  studying  them. 

It  is  said  that  there  is  no  impression  without  expression, 
and  to  supplement  the  work  of  the  recitation  in  this 
connection,  numerous  subjects  for  compositions  and  debates 
are  given.  It  is  hoped  that  the  teacher  will  not  allow  his 
classes  to  lose  the  interest  and  enjoyment  that  the  reading 
of  these  essays,  and  debates  at  regular  intervals,  always 
bring.  It  is  suggested  that  "  match  reviews  "  (an  adap- 
tation of  the  old-style  spelling  match),  "  competitive  drills," 
written  exercises,  and  other  forms  of  review  be  used. 

It  seems  to  the  author  that  the  time  has  come  for  a 
more  natural  and  logical,  and  therefore  a  more  effective, 
presentation  of  the  subject  of  temperance  than  past  methods 
have  furnished.  In  this  book  the  purpose  is  to  present  the 


TO    THE    TEACHER  vti 

blessings  of  natural  incitants,  and  to  show  how,  if  these 
incitants  are  taken  advantage  of  by  a  healthful  mode  of 
living,  no  craving  for  poisonous  stimulants  need  ever  arise. 
In  other  words,  the  temperance  teaching  is  positive  rather 
than  negative ;  it  dwells  upon  happy  things  more  than 
upon  the  unhappy.  As  to  amount  and  arrangement  of 
the  space  devoted  to  temperance,  the  book  will  be  found 
to  comply  fully  with  the  laws  of  the  different  states  on 
this  subject. 

The  present  backward  state  of  methods  in  teaching 
physiology  is  probably  to  be  attributed  to  the  fact  that  the 
text-books  have  been  written  by  physicians,  who,  by  reason 
of  the  duties  of  their  noble  and  arduous  profession,  have  not 
had  time  or  opportunity  to  learn  much  about  teaching.  The 
point  of  view  of  their  profession  may  also  explain  why  so 
many  physiologies  are  written  from  the  standpoint  of  sick- 
ness instead  of  from  the  optimistic  standpoint  of  health 
and  strength. 

Language  and  mathematics  have  been  taught  in  the 
schools  for  centuries ;  the  majority  of  the  natural  sciences 
have  not  been  taught  for  more  than  half  a  century,  which 
is  all  too  short  a  time  in  which  to  learn  to  teach  them 
most  effectively.  The  present  book  is  an  effort  toward 
raising  physiology  as  a  disciplinary  study  to  the  plane  of 
grammar  and  arithmetic,  with  the  idea  also  that  the  reasoning 
required  in  the  many  exercises  will  help  to  more  thorough 
understanding,  and  therefore  better  remembrance,  of  what  is 
learned.  What  should  we  think  of  an  arithmetic  or  a  gram- 
mar in  which  every  question  was  explained,  every  exercise 
worked  out,  and  consequently  everything  a  matter  of 
memory  and  learning  by  rote  ?  Yet  in  exactly  this  way 
have  the  school  physiologies  been  written,  and  with  such 
books  the  teacher  has  had  small  chance  to  keep  the  pupils 
from  learning  physiology  by  rote. 

It  has  been  the  purpose  to  lead  the  pupil  to  approach 


Viii  TO    THE    TEACHER 

every  question  in  the  scientific  spirit.  This  means  careful 
observation,  candor  of  mind,  and  patient  suspension  of 
judgment  until  sufficient  grounds  for  a  conclusion  are 
forthcoming,  and  if  they  do  not  exist,  then  to  leave  the 
question  unsettled. 

The  recent  addition  of  tropical  islands  to  our  territory 
and  the  number  of  our  citizens  that  go  thither  in  military 
and  civil  service,  together  with  the  semi-tropical  climate  of 
our  Gulf  states,  have  led  the  author  to  deem  care  of  the 
health  in  warm  climates  a  topic  of  sufficient  importance  to 
require  special  references  to  it. 

Those  illustrations  which  are  not  original  are  taken 
from  the  works  of  Huxley,  Testut  (Anatomie  Humaine\ 
Kellogg,  Thornton,  Foster,  Fabre,  and  Sappe"e.  The  author 
has  taken  pleasure  in  designing  the  colored  plates  and 
manikin,  as  so  many  schools  lack  facilities  for  instruction 
and  as  dissections  are  seldom  advisable.  The  handsome 
execution  of  the  numerous  line  engravings  and  colored 
plates  testifies  to  the  liberality  of  the  publishers  and  to  their 
purpose  to' place  this  work  in  the  schools  in  the  form  most 
useful  and  instructive  to  the  pupils. 

Sincere  thanks  are  returned  to  the  following  persons  for 
valuable  aid  in  reading  the  proof  :  W.  S.  Carter,  M.D., 
Franklin  W.  Barrows,  M.D.,  Alfred  Patton,  M.D.,  J.  W. 
Thomason,  M.D.,  J.  Philip  Gibbs,  M.D.,  D.  W.  Lewis,  A.M., 
H.  C.  Pritchett,  A.M.,  Mrs.  Rosa  Buchanan,  Miss  L.  W. 
Elliott,  Miss  A.  Lawrence,  and  Professor  R.  B.  Halley. 


CONTENTS 

PART    I 

INTR  OD  UCTOKY  KNO  WLED  GE 
CHAPTER   I 

PAGE 

THE  SKIN i 

CHAPTER   II 
CELLS  AND  TISSUES 25 

CHAPTER   III 
THE  SUPPORTING  TISSUES -34 

CHAPTER   IV 
THE  MASTER  TISSUES 44 

CHAPTER   V 
SUBSTANCES  FORMING  THE  BODY;  OXIDATION.        .        .        -51 

PART  II 

HOW   THE  BODY  IS  MOVED 

CHAPTER   VI 
THE  SKELETON 56 

CHAPTER   VII 
THE  CIRCULATION  82 


CONTENTS 


CHAPTER   VIII 

PAGE 

THE  CIRCULATION — continued  .  101 


CHAPTER   IX 
THE  MUSCLES 119 

PART    III 

HOW   THE  BODY  IS  NOURISHED 

CHAPTER   X 
THE  RESPIRATION 147 

CHAPTER  XI 
HYGIENE  OF  RESPIRATION 163 

CHAPTER  XII 
FOOD 193 

CHAPTER  XIII 
THE  DIGESTION 204 

CHAPTER  XIV 
HYGIENE  OF  DIGESTION 236 

CHAPTER  XV 
STIMULANTS  AND  NARCOTICS     .        ,         .        . 


CONTENTS  XI 

PART   IV 

HOW  THE  BODY  IS  CONTROLLED 
CHAPTER   XVI 

PAGE 

THE  NERVOUS  SYSTEM 282 

CHAPTER  XVII 
SOME  SPECIAL  REGULATIVE  PROCESSES 320 

CHAPTER  XVIII 
THE  SPECIAL  SENSES 334 

APPENDIX 
EMERGENCIES -355 


ELEMENTS  OF  PHYSIOLOGY 


PART  I.    INTRODUCTORY  KNOWLEDGE 
CHAPTER  I 

THE  SKIN 

1.  The  skin  that  covers  our  bodies  is  elastic  and  in  this 
respect  is  like  India  rubber.     But  if  they  are  both  exam- 
ined under  the  microscope,  a  marked  difference  is  found. 
Rubber  resembles  oil  and  water  in  being  alike  in  all  its 
parts,  while  the  skin  is  composed  of  an  immense  number 
of   small    objects   fitting  together.     Hence   it   is   said   to 
have  a  definite    structure,  while  rubber  has  not.     These 
small  objects  are  called  cells  and  fibers:  fibers  are  usually 
thread-like,  while  cells  are  of  various  shapes.     In  another 
chapter  it  will  be  learned  that  each  cell  has  life  and  activity 
of  its  own,  and  that  the  fibers  are  believed  to  be  branches 
from  the  cells.     A  number  of  cells  or  a  number  of  fibers, 
or  both  together,  make  what  is  called  a  tissue.     The  tissues 
form  organs.     An  organ  is  a  part  of  the  body  that  has 
special  work  to  perform  and  this  work  is  called  its  function. 
The  skin  is  an  organ  and  its  chief  function  is  to  protect 
the  body.    Name  the  organ  of  sight.    What  is  the  function 
of  the  teeth  ?    A  number  of  organs  working  together  for  a 
similar  end  is  called  a  system.     Thus  the  organs  which 
prepare  the   food  constitute  the  digestive  system ;   those 
which  circulate  the  fluids,  the  circulatory  system. 

2.  The  skin  consists  of  two  layers  (Fig.   i),  the  outer 
layer,  or  epidermis,  resting  on  the  inner  layer,  the  dermis, 

B  i 


ELEMENTS   OF  PHYSIOLOGY 


or  cutis.  The  dermis  is  called  also  the  true  skin.  The 
epidermis  is  composed  of  a  mass  of  cells  held  together 
by  a  cement  something  like  the  white  of  an  egg.  Those 
near  the  surface  (Fig.  2)  are  hard  and  flattened; 
those  deeper  down,  near  the  dermis,  are  round  and 
soft.  The  lowest  layers  contain  a  pigment  con- 
sisting of  minute  grains  of  coloring  matter.  The 

varying  amount  of  this 
pigment  present  causes 

Epider-     i      ' 

mis  or   the  difference  in  hue  of 
Cutide   the  blonde  and  brunette 


Sweat 
Glands 


Dermis     ^^^ 
or 

races.  Freckles  are  due 
to  an  increase  of  pig- 
ment in  patches  of 
neighboring  cells.  Some 
persons  lack  the  pig- 
ment entirely;  their  hair 
and  skin  are  white,  the 
eyes  pink.  They  are 
called  albinos.  Albinos 
are  found  among  vari- 
ous species  of  animals. 
Among  the  specimens 
in  the  British  Museum 
there  are  albino  (or  pure 
white)  blackbirds,  tur- 
keys, etc. 

3.  The  main  part  of  the  skin  is  the  dermis,  or  cutis 
(Fig.  i);  it  is  chiefly  a  network  of  fibers.  This  is  the  part 
of  the  skin  of  animals  that  is  tanned  for  leather.  Did 
you  ever  notice  the  fibrous  appearance  in  the  leather  of  a 
shoe  that  has  become  much  worn?  Which  side  of  leather 
is  smooth,  the  side  covered  by  epidermis,  or  the  other  side  ? 
The  human  skin  when  tanned  is  said  to  make  a  leather 


Nutrient  A  rtery 
FIG.  i.  —  Sectional  View  of  the  Skin,  magnified. 

Find:  oil  (sebaceous)  gland,  sweat  gland,  sweat  duct, 
hair  bulb.  Compare  thickness  of  epidermis,  dermis, 
and  subcutaneous  tissue.  (Thornton.) 


THE   SKIN 


resembling  the  pigskin  of  which  footballs  are  made.  The 
dermis  is  connected  with  the  body  beneath  by  a  loose  tissue 
consisting  of 
fibers  inter- 
woven with  cells 
of  fat  (Fig.  i). 
This  tissue,  to- 
gether with  the 
skin  itself,  partly 
conceals  the  out- 
lines  of  the 
muscles  be- 
neath.  Yet 
artists  study  the 
muscles  care- 
fully, as  their 
shape  shows 
faintly  through 
the  skin  and 
gives  a  key  to 
the  human 
figure. 

4.  The  outer 
surface  of  the 
dermis  grows 
into  numerous 
little  projections 
called  papillae 
(Figs,  i  and  2). 
If  its  covering 


FIG.  2.  —  Diagram  to  show  the  Structure  of  the  Skin. 

E.c,  epidermis  corneous  part;  E.m,  epidermis  Malpighian  part; 
D.c,  connective  tissue  of  dermis;  /,  papilla;  gl,  sweat  gland, 
the  coils  of  the  tube  cut  across  or  lengthwise;  dt  its  duct;_/, 
fat;  -v,  blood  vessels;  n,  nerve;  t.c,  tactile  corpuscle. 


of  epidermis 
were  taken  off, 

the  dermis  would  appear  somewhat  like  coarse  velvet  be- 
cause of  its  unevenness ;  for  the  prominences  or  papillae 
appear  under  the  microscope,  in  a  cross-section  of  the  skin, 


ELEMENTS   OF  PHYSIOLOGY 


buried  beneath  the  cells  of  epidermis,  like  a  tiny  moun- 
tain range.  As  the  epidermis  fills  up  the  valleys  between 
them,  the  papillae  do  not  show  plainly  on  the  surface 
of  the  skin.  However,  on  the  palm  of  the  hand  and 
the  fingers,  where  the  papillae  are  especially  numerous, 
they  are  crowded  into  rows,  their 
position  being  shown  by  the  paral- 
lel ridges  seen  on  the  epidermis  of 
the  palm.  Within  the  papillae  are 
found  the  ends  of  nerves  and  loops 
of  small  blood  vessels  called  capil- 
laries (Figs.  2  and  3). 

The  cells  of  the  epidermis  which 
lie  next  to  the  dermis  are  living  cells. 
They  are  kept  alive  by  nourishment 
brought  by  the  watery  portion  of 
the  blood  in  the  blood  vessels  of  the 
neighboring  papillae.  These  cells 
are,  therefore,  growing  cells,  and 
when  they  grow  to  a  certain  size, 
each  cell  subdivides  into  two.  (The 
way  in  which  the  cells  form  new  cells 
will  soon  be  studied  in  another 


FIG.  3.  —  Diagram  of  Epi- 
dermis and  Upper  Part  of 
Dermis. 

Showing  nerve, «,  and  tactile  cor-   chapter.)     This  multiplication  of  the 

pu.cle,  t.ct  or  organ  of  touch;  jj  M  th       epidermis    tO 

also  sweat  tube,  d. 

increase  greatly  in  thickness,  were 

not  the  outer  cells  constantly  worn  away  by  friction.  This 
more  easily  happens  as  the  outer  cells  are  dead  cells.  The 
new  cells  forming  beneath  push  them  so  far  away  from 
the  dermis,  that  nourishment  from  the  blood  no  longer 
reaches  them,  and  they  die. 

By  this  constant  loss  and  renewal,  the  body  always 
has  a  comparatively  new  outer  skin.  Even  on  the  scalp, 
which  is  partly  protected  from  friction,  the  flat  dry  cells 
are  constantly  coming  off.  If  there  is  much  oil  on  the 


THE  SKIN 


scalp,   the    cells    stick    together    and   form   flakes   called 
dandruff. 

5.  Organs  in  the  Dermis.  —  The  tough,  flexible  sheet 
called  the  dermis  is  called  by  what  other  name  ?     Lodged 
among   its   fibers   and   supported   by  them   (Fig.  2)  are 
(i)  a  fine   network  of  blood  vessels;  (2)  a  fine  network 
of  nerves;  (3) several 

million  sweat  glands; 
(4)  a  great  number  of 
oil  glands.  Suppose 
you  were  to  stick  a 
pin  into  the  true  skin. 
You  would  find  evi- 
dence that  you  had 
wounded  which  two 
of  these  possessions 
of  the  true  skin  ?  Are 
they  so  numerous  that 
you  could  penetrate 
the  skin  anywhere 

without        Striking    FIG.  4.  —  Coiled  End  of  a  Sweat  Gland,  Epidermis 

them?     You  learned 

that    the    dermis    is 

composed    chiefly   of 

fibers,  and  that  the  epidermis  is  composed  of  cells. 

cells  are  very  simple  and  are  called  epithelial  cells. 

6.  The  Sweat  Glands,  or  perspiratory  glands  (Figs,    i 
and  4),  are  little  tubes,  lined  with  epithelial  cells,  which 
pass  through  the  epidermis  and   down  into  the  dermis. 
The  tube  is  coiled  into  a  ball  in  the  true  skin,  where  it  is 
surrounded  by  a  network  of  capillaries.     Its  course  through 
the  epidermis  is  spiral  like  the  turns  of  a  corkscrew.     Its 
opening  on  the  surface  is  called  a  pore.     The  coiled  part 
is  supplied  with  nerves  which  stimulate  the  cells  to  secrete 
the  perspiration.     The  cells  obtain  their  supply  of  material 


not  shown. 

,  the  coil;  b,  the  duct;  c,  network  of  capillaries,  inside 
of  which  the  gland  lies.  Does  the  sweat  gland  lie  in 
the  skin  or  beneath  the  skin?  (See  Fig.  i.) 


These 


6  ELEMENTS   OF  PHYSIOLOGY 

from  the  blood  so  freely  furnished  them.  This  supply 
is  controlled  by  the  nerves  which  regulate  the  size  of  the 
arteries  leading  to  the  skin.  The  sweat  glands  take  up 
water  and  various  other  substances  from  the  blood  and 
pour  them  out  upon  the  surface  of  the  true  skin.  The 
water  evaporates,  but  the  salt  and  other  solids  in  the  per- 
spiration are  deposited  on  the  skin ;  just  as  salt  will  not 
evaporate  from  the  ocean,  and  as  solids  form  in  the  bottom 
of  a  kettle  of  boiling  water.  Usually  the  amount  of  per- 
spiration from  each  gland  is  so  small  that  it  evaporates, 
or  is  dried  up  by  the  air,  as  soon  as  it  reaches  the  surface,  and 
hence  does  not  become  visible.  On  this  account  it  is  called 
insensible  perspiration ;  it  becomes  sensible  perspiration 
when  it  is  formed  rapidly  in  warm  weather  or  during  vigor- 
ous exercise.  It  does  not  evaporate  so  quickly  in  a  moist 
atmosphere ;  and  those  who  live  near  the  seacoast  or  in 
rainy  regions  show  more  perspiration  than  those  who  live 
in  dry  regions,  although  the  former  may  not  perspire  so 
much.  The  amount  of  perspiration  averages  about  one 
and  one  half  pints  per  day.  In  the  study  of  physics,  we 
are  taught  that  the  evaporation  of  even  a  small  amount 
of  water,  as  from  a  teakettle,  uses  up  a  large  amount  of 
heat.  Hence,  perspiration  is  very  effective  in  cooling  the 
body. 

Why  is  humid  weather  in  summer  so  oppressive  and 
disagreeable  ?  Is  the  skin  more  active  in  throwing  off 
impurities  in  winter  or  in  summer  ?  The  mucous  membrane 
is  a  kind  of  inner  skin,  lining  the  nose,  throat,  and  all 
inner  passages  to  which  air  has  access.  In  case  of  need, 
when  the  skin  fails  to  act  and  ceases  to  throw  off  the  usual 
amount  of  impurities,  the  mucous  membrane  may  become 
swollen  with  blood  and  throw  off  impurities  in  the  form 
of  phlegm  and  mucus.  Such  a  condition  is  called  a  cold. 

7.  The  Number  of  Sweat  Glands.  —  Count  the  sweat 
glands  shown  in  Figure  5.  This  row  is  one  half  inch  long. 


THE   SKIN 


Skin  from  the  Palm 
of  the  Hand,  natural 
size. 

i,  epidermis  ;  2,  papillae  ; 
3,  dermis  ;  4,  subcutane- 
ous tissue  and  sweat 
glands. 


To  get  the  number  in  one  square  inch,  multiply  by  itself 

the    number   in  a  row  one  inch  long.     There  are  about 

2,400,000  sweat  glands  in  the  entire  body.     They  are  most 

numerous    in    the    palm.      If    a    sweat 

gland  averages  one  fourth  inch  in  length, 

how  many  miles  would  they  extend  if  FIG.  5.  — section  of  the 

placed  end  to  end  ? 

8.  THOUGHT  LESSON.  Anatomy  and 
Physiology  of  the  Skin.  —  i .  What 
fraction  of  an  inch  in  thickness  do  you 
judge  the  skin  on  the  back  of  the  hand 
to  be  ?  (A  fold  shows  double  thickness.) 

2.  Feel  and   observe  the  skin,  and  write   five  qualities 
possessed  by  it. 

3.  What  evidence  have  you  ever  had  that  the  skin  has 
two  layers  ? 

4.  How  long  will  a  pair  of  kid  gloves  last  ?     What  does 
this  suggest  about  the  skin  ? 

5.  State  a  fact  which  shows  that  the  skin  gives   out 
offensive  substances. 

6.  State  -a  fact  which  shows  that  the  skin  is  a  protection. 

7.  State  a  fact  which  shows 
that  the  skin  is  a  regulator  of 
temperature. 

8.  Are  wrinkles  a  sign  that 
the  skin  is  too  tight  or  too  large 
and  loose  for  what  it  covers  ? 

9.  The  loss  of   what  tissue 
causes  wrinkles  ? 

9.  Hair.  —  Sometimes  a  pa- 
pilla, instead  of  being  on  the 
surface  of  the  dermis  on  a  level  with  other  papillae,  is  at 
the  bottom  of  a  pit  or  bag  called  a  follicle  (Fig.  7).  A 
column  of  epithelial  cells  forming  a  hair  grows  from  this 
papilla,  and  the  papilla  is  sometimes  called  the  root  of 


FIG.  6.  —Surface  of  the  Palm, 
magnified. 

Showing  ridges  and  pores,  or  openings, 
of  the  sweat  glands. 


8 


ELEMENTS  OF  PHYSIOLOGY 


the  hair.  A  hair,  therefore,  grows  from  the  top  of  a 
papilla  which  stands  in  the  bottom  of  a  pit  in  the  true 
skin.  The  outside  of  the  hair  is  formed  of  colorless,  over- 
lapping cells  (Fig.  7).  The  hair 
„  is  pithy  in  the  center  and  contains 

l^flHB™     pigment  cells.     In  old  people,  the 
£:v^  pigment  is  replaced  by  air,  and  the 

mj      *  hair  turns  white.     The  only  point 

I  w,  ^  at  which  the  cells  of  the  hair,  and 

therefore  the  hair  itself,  are  living 
and  growing  is  at  the  top  of  the 
papilla,  deep  down  in  the  follicle 
(Fig.  7).  From  this  it  is  easy  to 
see  that  the  common  notion  that 
cutting  off  the  ends  of  the  hair, 
either  by  shaving  or  trimming  with 
scissors,  causes  it  to  grow  faster 
and  stronger,  is  erroneous.  It 
may  stop  the  splitting  of  hairs  and 
thus  prevent  the  wearing  away  of 
the  hair.  Of  course  when  the  hair 
or  beard  is  short,  its  growth  is 
more  noticeable.  Long  hair  seems 
by  its  weight  to  give  exercise  to 
minute  muscles  in  the  skin  and 
strengthen  the  flow  of  blood,  thus 
FIG.  7. -A Hair  in  its  Follicle,  adding  to  the  vigor  of  the  hair. 
^^h.tS^^  The  cut  end  of  a  hair  is  nearly 
cst  portion  of  ths  hair  growing  round  in  the  straight-haired  races, 

on  the  papilla  z  ;    a,  cuticle  of  t  ... 

hair;    e,  cavity  of  hair  follicle;      as    Indians    and    ChinCSC  J    it  is  OVal 

ft    epidermis    of    follicle    corre-  -  .       .       j         ,   .  j 

to  «,,  the  epidermis    in  the  wavy-haired  white  race,  and 

S'A-^SiS  flattened  stm  more  in  the  kinky- 

k,  dermis  of  foiiicie  correspond-    haired   negro  race.     Which  races 

ing  to  dermis,  /,  near  the  surface ;  .  1-1 

k,  mouths  of  sebaceous  or  oil    have  black  hair  ?     In  which  races 
*'  h°rny  CpidermiS  at    is  the  color  of  the  hair  variable  ? 


THE  SKIN 


10.  Hair   is   very   durable ;    that    found    on    Egyptian 
mummies  has  remained  unchanged  through  several  thou- 
sand years.     It  is  elastic  and  is  said  to  stretch  one  third 
of   its  length  without   breaking.     Find  out  whether  this 
is   true  by   attaching   weights   to  a   hair.     Hair   absorbs 
moisture  readily,  and  for  a  time  its  length  is  considerably  in- 
creased thereby.     Each  hair  follicle  has  fine  muscles  con- 
nected with  it.     Cold  or  fear  may  cause  the  muscles  to 
contract  and  the  hairs,  which  are  usually  in  a  slanting  posi- 
tion, to  stand  erect.     This  causes  the 

hair  to  afford  a  better  protection  to  the 
animal  from  cold  or  blows.  "  Goose 
skin,"  which  occurs  if  a  cold  bath  is 
unduly  prolonged,  is  caused  in  the 
same  way ;  but  the  hair  on  the  human 
skin  is  so  fine  that  the  goose  skin 
avails  little  against  cold. 

11.  The  Oil  Glands,  or  sebaceous 
glands,  are  small,  irregularly  shaped 


FIG.  8.  — Piece  of  Human 
Hair,  magnified. 

Cavities     Which     Open    intO    the    little      A,  seen  from  the  surface.     B,  in 

section,  c,  cuticle;  m,  pith, 
the  air  having  been  expelled  by 
Canada  balsam. 


pits  from  which  the  hairs  grow  (Fig. 
i).  A  few  oil  glands  open  directly 
upon  the  surface.  They  are  lined  with  epithelial  cells. 
The  cells  deposit  a  kind  of  oil,  which  flows  out  of  the 
mouth  of  the  glands,  renders  the  epidermis  flexible  and 
less  penetrable  by  water,  and  prevents  it  from  drying  out 
by  evaporation  and  cracking  open.  It  is  also  the  natural 
"  hair  oil,"  for  softening  the  hair  and  keeping  it  from 
becoming  brittle.  The  oil  glands  of  the  center  of  the  face 
are  especially  large  and  numerous.  When  their  mouths 
are  stopped  by  dirt,  they  become  distended  with  oily  mate- 
rial and  are  called  blackheads.  Oil  glands  are  absent  from 
the  soles  and  palms. 

12.  The  Nails,  as  well  as  the  hair,  are  a  growth  of  the 
epidermis ;  and  like  the  epidermis,  only  the  lowest  cells, 


10 


ELEMENTS   OF  PHYSIOLOGY 


The  skin  covering  the  base  of  that  the  nail  is  renewed  in 

the  nail  is  cut  back. 

four  months. 


near  their  roots,  are  alive  and  receive  nourishment.  The 
root  of  the  nail  is  in  a  kind  of  groove  or  fold  of  the  true 
skin  (Fig.  9)  at  the  bottom  of  which  papillae  are  very 
numerous.  The  nail  may  be  regarded  as  a  very  wide,  flat 
hair.  The  nail  grows  not  only  at  its 
root,  but  along  its  bed  which  is  of  true 
skin  (Fig.  10).  Hence,  its  thickness 
increases  as  it  approaches  the  tip.  If 
the  epidermis  is  pressed  back  at  the 
root,  the  nail  may  not  be  perfectly 
nourished,  and  a  white  speck  or  flaw 
is  formed,  which  travels  slowly  along 
FIG.  9.  — End  of  Finger,  with  the  growth  of  the  nail.  It  is  said 

three  or 

If  you  note  the  date  of 
the  appearance  of  a  scar  at  the  base  of  the  nail  and  note 
when  it  has  traveled  to  the  tip,  you  can  find  whether  this  is 
true.  Find  whether  or  not  a  nail  is  transparent,  by  looking 
through  the  tip  of  the  nail,  held  up  to  the  light.  The 
nails  stiffen  the  ends  of  the  fingers 
and  aid  in  handling  small  objects. 
Can  you  pick  up  a  pin  without 
using  the  nails  ?  Corresponding 
organs  in  the  lower  animals  are 
claws  and  hoofs.  The  epidermis 
forms  also  the  scales,  feathers,  and 
horns  of  the  lower  animals. 

13.    The    papillae    over    a    small 
area,  when  the  epidermis  is  weak, 

sometimes  become  overgrown,  so  that  they  project  above 
the  skin,  and  form  a  wart.  If  it  is  burned  away  with 
acid,  the  epidermis  will  grow  over  the  place.  Why  is  a 
wart  rough  ?  How  does  it  differ  from  a  mole  ?  Which 
is  more  likely  to  increase  in  size  ?  Which  has  more  pig- 
ment ?  Which  contains  hairs  ?  When  the  epidermis  is 


FIG.  io.  —  Section  of  Nail  and 
Parts  Beneath. 

I,  2,  4,  horny  layer  of  cuticle,  con- 
tinuous with  3,  the  nail;  9,  12, 
dermis. 


THE  SKIN  II 

broken  so  that  the  true  skin  is  exposed,  the  epithelial  cells 
at  the  edge  of  the  break  usually  produce  new  cells  to  cover 
and  heal  the  opening.  But  if  they  do  not  form  new  cells, 
the  true  skin  sprouts  through  the  opening,  forming  proud 
flesh,  which  must  be  scraped  off  or  cauterized  before  the 
epidermis  can  complete  the  healing.  In  the  case  of  a 
blister,  the  lowest  cells  of  the  epidermis  are  not  removed ; 
hence  the  epidermis  is  readily  renewed.  Sometimes  super- 
fluous hair  grows  on  the  upper  lip  of  a  lady,  on  moles, 
or  on  unusual  parts  of  the  face.  To  remove  this  hair 
so  that  it  will  not  grow  again,  the  papillae  at  the  bot- 
tom of  the  follicles  must  be  destroyed.  This  is  no  easy 
matter.  Numerous  "  infallible  "  remedies  are  advertised, 
but  the  only  effective  way  is  by  means  of  the  electric 
needle,  a  needle  which  transmits  an  electric  current. 

14.  THOUGHT  LESSON.  Hygiene  of  the  Skin. —  i.  What 
is  lacking  in  the  skin  when  it  cracks  or  chaps  ?  How  could 
chapping  be  prevented  in  another  way  than  by  using 
cream,  etc.  ? 

2.  Why  does  the  skin  chap  in  cold  weather  more  often 
than  in  warm  weather  ? 

3.  How  does  perspiration  cool  us?1 

4.  Why  do  we  perspire  more  freely  when  we  exercise  ? 

5.  Why   do   we    perspire   more    freely   when   we    are 
warm  ? 

6.  Is  it  more  necessary  for  mental   workers   to  bathe 
often,  or  to  change  their  clothes  often  ? 

7.  Which  is  more  necessary  for  physical  workers  ? 

8.  Do  you  know  of  persons  who  burn  their  hair  with 
hot  irons  ?     What  is  the  effect  upon  the  hair  of  repeated 
scorching  ? 

1  Do  not  try  to  answer  this  unless  you  have  studied  elementary  physics.  A 
knowledge  of  that  subject  will  enable  you  to  understand  why  wetting  the  feet 
even  with  warm  water  causes  colds  more  quickly  than  a  draft  of  cool  air  upon 
the  feet. 


12 


ELEMENTS  OF  PHYSIOLOGY 


FIG.  ii. 

A,  typical   structure  of  a  mucous 
membrane  with  two  layers  of  epi- 
thelial cells,  a,  6;    c,  the  connec- 
tive tissue  beneath,  with  e,  blood- 
vessels, and  ft  connective  tissue 
cells. 

B,  the  same  with  one  layer  of  cells 
resting  on  3,  the  so-called  base- 
ment membrane. 


FIG.   12. 

A  simple  tubular  gland  with  blood- 
vessel. 


FIG.  13. 

A  tubular  gland  dividing. 


FIG.    14. 
A  sac-like  gland. 

Diagrams  to  illustrate  the  Struc- 
ture of  Glands. 


15.  The    Mucous    Membrane.  — 

Epithelial  cells  form  not  only  the 
epidermis  to  cover  the  body  exter- 
nally, but  they  form  also  a  lining 
for  the  interior  cavities  of  the  body. 
Any  interior  cavities  to  which  air 
has  access,  as  the  mouth,  stomach, 
and  lungs,  are  lined  with  one  or 
more  layers  of  closely  packed  epi- 
thelial cells  called  mucous  mem- 
brane. Any  cavities  from  which 
the  air  is  cut  off,  as  the  heart,  are 
called  serous  cavities,  and  have  a 
lining  of  epithelial  cells  forming 
what  is  called  a  serous  membrane. 
These  membranes  secrete  a  lubri- 
cating fluid.  The  fluid  formed  by 
the  mucous  membrane  is  called 
mucus.  The  line  where  the  epi- 
dermis and  the  mucous  membrane 
of  the  lips  join  can  be  plainly  seen, 
as  the  latter  membrane  is  so  thin 
that  the  color  of  the  blood  shows 
through  it.  Mucous  membranes 
are  so  smooth  and  their  cells  are  so 
tightly  packed  that  they  are  harder 
to  cut  than  the  skin,  notwithstand- 
ing they  are  very  thin. 

16.  Glands  (Figs.  11  to  17)  are 
always  lined  with  epithelial  cells. 
Glands  are    cavities  in  the  body, 
usually    bag-shaped     or     tubular, 
whose  walls   secrete  fluids  which 
are  of  various  uses  in  the  body. 
The  gland  cells  make  use  of  the 


THE  SKIN 


various  chemical  substances  in  the  blood,  so  that  one  gland 
secretes  oil,  another  perspiration,  another  saliva,  etc.  The 
kidneys  are  important  glands  which  resemble  some  of  the 
glands  of  the  skin  in  that  they  secrete  injurious  substances 
that  must  be  removed  from  the  system.  Secretion  is  the 
name  given  the  various  fluids  formed  by  glands.  Excre- 


FIG.  15. 

A  divided  saccular  gland  with  duct,  d. 


FIG.  16. 

A  similar  gland  more  divided. 


FIG.  17. 

A  racemose  or  branching  gland,  part  only 
being  shown. 


More  Diagrams  to  illustrate  the  Structure  of  Glands. 

tion  is  a  secretion  of  harmful  substances  to  be  removed 
from  the  body. 

17.  Secretion  is  not  simply  a  process  of  soaking  or  sift- 
ing through.  The  walls  of  the  glands  are  made  of  cells. 
The  cells,  those  wonderful  little  bodies  which  we  shall  study 
more  carefully  in  another  chapter,  obtain  from  the  blood 
the  materials  which  they  secrete.  More  than  this,  by  the 
aid  of  the  nerves,  they  can  regulate  the  amount  of  secretion 


14  ELEMENTS   OF  PHYSIOLOGY 

independently  of  the  amount  of  blood  circulating  around 
them,  although  usually  the  amount  of  secretion  is  greatly 
influenced  by  the  amount  of  blood  in  the  skin  (Fig.  2). 
Sometimes  the  skin  is  hot  from  the  abundance  of  blood 
flowing  through  it,  as  during  a  fever,  but  it  is  dry  as  well 
as  hot  because  the  sweat  glands  are  not  acting.  A  dog 
does  not  perspire  except  through  the  soles  of  its  feet  and 
through  its  tongue.  Once  a  curious  experiment  was  tried 
upon  a  dog  in  which  the  nerves  supplying  one  foot  had 
been  severed.  This  dog  was  placed  in  a  very  hot  chamber. 
Three  of  its  feet  perspired  profusely ;  but  the  foot  which 
lacked  nerves  to  control  its  sweat  glands  was  perfectly 
dry.  This  shows  that  nervous  control  as  well  as  heat 
is  necessary  to  make  the  gland  cells  perform  their  func- 
tions. Sometimes,  under  the  influence  of  excitement  or 
fear,  a  person  breaks  out  in  a  profuse  perspiration,  which 
is,  however,  cold,  for  there  is  little  blood  in  the  skin. 

18.  Stimulants  and  Narcotics.  —  A  stimulant  is  a  sub- 
stance that  is  usually  an  enemy  to  the  welfare  of  the  body; 
it  irritates  and  excites  when  first  taken.  This  is  because 
of  the  effort  of  the  system  to  expel  it.  After  such  effort, 
the  body  is  weaker  and  more  sluggish  than  before.  This 
effect  is  called  the  reaction.  There  is  no  known  stimulant 
that  does  not  cause  a  reaction.  A  narcotic  is  a  substance 
that  deadens  the  nerves;  this  effect  does  not  come  as  a 
reaction,  but  begins  as  soon  as  the  narcotic  is  taken. 
Strychnine  is  a  stimulant ;  tobacco  is  a  narcotic.  How 
alcohol  is  apparently  a  stimulant  but  really  a  narcotic  will 
be  explained  in  another  chapter.  The  toper  is  said  to 
have  a  "  rum  blossom  "  on  his  nose.  This  swollen  condi- 
tion of  the  blood  vessels  of  the  nose  is  caused  by  the  para- 
lyzing action  of  alcohol  upon  the  walls  of  the  blood  vessels. 
The  stagnant  circulation  allows  the  blood  to  become  purple 
with  impurities.  Coffee-drinking  often  causes  the  com- 
plexion to  be  "muddy."  Have  you  ever  noticed  any  differ- 


THE  SKIN 


ence  between  the  skins  of  those  who  use  coffee  and  those 
who  do  not  ?  Tobacco  has  an  effect  similar  to  that  of  coffee. 
The  injury  that  coffee  and  tobacco  do  to  the  stomach  and 
liver  causes  the  blood  to  be  impure,  and  the  effect  of  im- 
pure blood  usually  shows  in  the  complexion. 

19.  The  Teeth  may  be  regarded  as  a  part  of  the  skin, 
since  a  tooth,  like  a  hair  or  a  nail,  is    developed  from  a 
papilla  of  the  true  skin.      A  tooth  extends  down  into  a 
depression  in  the  jawbone,  called  a  socket,  and  is  held  in 
place  largely  by  the   tightness  with  which  the  root,   or 
lower  part,  fits  into  the  socket.     The  visible  part  of  the 
tooth  is  called  the  crown. 

20.  Number  and  Names  of  the  Teeth.  —  A  complete  set 
of  teeth  in  adults  consists  of  sixteen  in  each  jaw  or  thirty- 
two  in  all.      They 

are  named  accord- 
ing to  their  form 
and  the  uses  to 
which  they  are 
adapted.  There 
are  eight  (Fig.  18) 
in  each  quarter  of 
the  mouth  ;  and  if 
the  names  of  the 


FIG.  18.  — Teeth  from  One  Side  of  the  Lower  Jaw 

of  Man. 
i,  incisors;  z,  canine;  3,  bicuspids;  4,  molars. 


eight  in  one  quarter  are  learned,  you  know  the  names 
of  the  thirty-two,  since  they  are  designated  by  the  same 
names,  in  the  same  order  in  each  quarter  of  the  mouth. 
Looking,  then,  at  the  teeth  in  one  half  of  one  jaw  and 
naming  them  in  order  from  front  to  back,  there  are  two 
incisors,  one  canine,  two  bicuspids,  and  three  molars. 
How  many  of  each  kind  are  found  in  the  whole  mouth 
(Fig.  18)?  The  eight  in  front  are  for  cutting  off  the  food, 
and  hence  are  called  incisors,  or  cutters.  They  have  chisel- 
like  edges.  Do  the  edges  of  the  upper  and  the  lower 
teeth  usually  meet  in  the  mouth,  or  do  they  miss  each 


i6 


ELEMENTS   OF  PHYSIOLOGY 


other  like  the  blades  of  scissors  ?  The  incisors  are  very 
long  in  gnawing  animals  (rats,  squirrels,  etc.).  Next  to 
the  two  incisors  in  each  quarter  of  the  jaws,  comes  one 
canine,  so  called  because  the  corresponding  tooth  in  the 
jaws  of  dogs  is  well  developed ;  in  cats,  tigers,  dogs,  and 
other  flesh-eating  animals,  it  is  suited  for  tearing.  It 
has  only  one  root,  but  that  is  a  long  one.  Could  you 
catch  hold  with  your  canine  teeth  so  as  to  use  them  for 
tearing  ?  Are  they  sharper  than  the  incisor  teeth  ?  (Use 


FIG.  19. 

a  mirror.)  The  two  upper  canines  are  fancifully  called  the 
"eye  teeth,"  and  the  two  lower,  the  " stomach  teeth."  Next 
in  order  behind  the  canines  are  the  two  bicuspids,  which 
are  grinding  teeth.  Their  crowns  are  broad  and  they 
have  two  roots.  Last  of  all  come  the  three  large  grinders, 
called  molars.  Are  the  grinding  surfaces  of  the  molars 
smooth  or  rough  ?  Are  they  like  or  unlike  the  surfaces 
of  the  bicuspids  ?  The  last  molar  in  each  jaw  is  called 
the  wisdom  tooth,  because  these  teeth  do  not  come  until 
the  person  is  supposed  to  have  reached  years  of  dis- 
cretion. Activity  is  the  law  of  life,  and  the  wisdom  teeth 


THE  SKIN 


Enamel  worn 
away 


Crown 


Neck 


are  so  far  back  in  the  mouth  that  they  are  not  much 
used ;  therefore  they  do  not  usually  remain  so  long  as  the 
others, 

21.  Milk  Teeth.  —  The  teeth  just  described  are  those 
of   the    permanent  set.      The   first   or   temporary  set   of 
teeth  (Fig.   19)  consists  of  teeth  the  same  in  name  and 
number  as  those  of  the  permanent  set  except  that  the 
three  large  molars  in  each  half  jaw, 

twelve  in  all,  are  lacking;  so  there 
are  twenty  teeth  in  the  temporary 
set  (Fig.  19).  The  milk  teeth  come 
during  the  first  two  years  of  life,  and 
begin  during  the  sixth  or  seventh 
year  to  be  pushed  out  and  replaced 
by  the  permanent  teeth.  They  are 
all  gone  by  the  twelfth  year.  The 
milk  teeth  have  much  smaller  roots 
than  the  permanent  teeth.  Since 
a  tooth  does  not  enlarge  after  it 
develops,  the  two  sets  of  teeth  are 
a  beautiful  provision  for  preserving 
the  regularity  of  the  teeth  as  the 
jaws  increase  in  size.  If  a  milk 
tooth  remains  so  long  as  to  cause 
the  tooth  of  the  second  set  to  grow 

r       i  .-i        r-  ,1        i_       11    FIG.  20.  —  Vertical  Section  of  a 

OUt   Of    place,  the    first   tOOth    Should       Bicuspid  Tooth,  magnified. 

be  removed. 

22.  The  main  part  of  the  body  of  a  tooth  is  dentine  (Fig. 
20).    The  dentine  of  the  teeth  of  elephants  and  other  large 
animals  is  the  ivory  of  commerce.     It  is  commonly  used 
on  piano  keys,  fans,  etc.     In  the  central  part  of  the  den- 
tine is  a  space  called  the  pulp  cavity.     The  soft  substance 
called  the  pulp  contains  the  nerves  and  blood  vessels  which 
enter  at  the  tip  of  the  root.     In  the  socket  the  dentine 
is  covered  by  cement;   above  the  socket  it  is  covered  by 

c 


Fang 


i8 


ELEMENTS   OF  PHYSIOLOGY 


enamel,  a  substance  harder,  denser,  and  more  shining  than 
the  dentine. 

23.  The  enamel  is  worn  off  from  the  top  of  the  crown 
between  the  twentieth  and  thirtieth  years.    (If  you  examine 

a  person's  mouth  in  whose  teeth  the 
yellowish  dentine  shows  through  the 
white  enamel,  you  will  know  that  per- 
son to  be  at  least  how  old  ?)  Although 
the  dentine  is  exposed  through  the 
wearing  or  breaking  of  the  enamel,  it 
will  last  for  years  without  decaying,  but 
it  is  more  likely  to 
decay  than  the  en- 
amel. We  should 
never  run  the  risk 
of  breaking  the 
enamel  by  sudden 
slipping  of  the 
teeth,  such  as  often 
occurs  when  eating 
hard  candies  or 
cracking  nuts.  A 
tooth  should  never 
be  pulled  if  it  can 

be  saved  by  being  filled  ;  for  pulling 
a  tooth  means  not  only  the  loss  of  one 
tooth,  but  the  end  of  usefulness  of  the 
tooth  opposite  to  it,  and  imperfect  chew- 
in  g  in  that  part  of  the  mouth.  Losing  FIG.  22.— Teeth  of  a  Cow 

fed  on  Slops. 

a  tooth  is  equivalent  to  losing  part  of   Showing  ^        Q{  eating 

the  life.  f°°d  that  requires  the  use 

24.  Decay  of  the  teeth  is  caused  ( i )  by 

using  only  soft  food  (Figs.  21  and  22)  which  requires  no 
pressure  of  the  teeth  while  chewing  it ;  (2)  by  particles  of 
food  lodging  between  the  teeth  and  becoming  quickly  de- 


FlG.  2i.— Teeth  of  a 
Healthy  Cow. 


THE   SKIN  19 

composed  in  the  warm,  moist  mouth;  (3)  by  the  collection 
of  tartar  on  the  teeth  (Fig.  23).  This  is  a  deposit  formed 
because  the  secretion  of  the  mouth  is  in  improper  condi- 
tion. It  affords  an  inviting  soil  in  which  germs  may  grow 
and  attack  the  teeth.  (4)  Constant  nibbling  of  candy  be- 
tween meals  is  a  bad  habit,  as  the 
sugar  may  ferment  in  the  mouth  and 
change  to  an  acid,  which  injures  the 
teeth. 

25.  A  toothbrush  is  more  effective 
when  it  is  rubbed  up    and  down  as 
well  as  across  the  teeth.      A  tooth- 

.  .          .       FIG.    23.  —  Human    Teeth ; 
pick  IS  as  important  as  a  toothbrush.          sockets   injured  by  tartar 

As  a  tooth  powder,  fine  precipitated       (°n  left) ;  uninjured  (on 
chalk  is  best;   it  helps  to  clean  the 

teeth  and  destroys  sourness  due  to  acids.  Do  you  like 
to  leave  the  table  with  a  sweet  taste  in  the  mouth  ? 
Why  does  chalk  injure  the  skin,  although  good  for  the 
teeth  ? 

26.  THOUGHT    LESSON.      The   Complexion.  —  i .    Draw 
lines  under  the  words  which  name  qualities  belonging  to 
a   healthy    skin  :    hard,  soft,  dry,  moist,   flexible,    elastic, 
firm,  flabby,  smooth,  dingy,  rough,  pink,  yellow,  pale,  vel- 
vety. 

2.  The and  the upon   the  skin  keep  it  from 

being  dry. 

3.  These  secretions  come  from  the—   —and  the . 

4.  The  organs  that   furnish  these  secretions  get  their 
material  from  the . 

5.  What  is  the  best  means  of  improving  the  circulation 
in  the  skin  ? 

6.  When  a  pore  is  so  full  of  dirt  and  oil  that  you  can 
see  it,  what  is  it  called  ? 

7.  You  have  considered  what  makes  the  skin  soft;  let 
us   think  what  will  make  it   dry  and  hard.     When    our 


2O  ELEMENTS  OF  PHYSIOLOGY 

grandmothers  were  young,  there  was  no  blotting  paper. 
What  did  they  keep  in  a  cup  on  the  writing  desk  to  dry 
the  ink  with  ?  Try  it. 

8.  To  what  similar  treatment   is   the   skin   sometimes 
subjected  ?     Why  do  dry  powders,  hot  winds,   and  over- 
heated rooms  all  have  a  similar  effect  upon  the  skin  ? 

9.  Think  of  five  girls  not  over  twelve  years  old.     How 
many  of  them  have  healthy  skins  ? 

10.  Of  the  first  five  grown  young  ladies  that  you  hap- 
pen  to   think   of,    how  many   have   smooth,   rosy  skins  ? 
How  many  have  dingy,  bad  complexions  ?     Have  any  of 
them  blotches  in  the  middle  of  the  cheek  ? l 

11.  The  skin  does  not  naturally  become  dry  or  dark- 
colored  with  age  until  after  middle  life.     What  have  the 
young  ladies  done  to  injure  their  soft,  rosy  complexions  ? 

12.  Why  are  such  young  ladies  not  bright? 

13.  Who  is  more  apt  to  be  sincere  in  nature,  a  person 
with  a  clean  face  and  a  truthful  complexion,  or  one  who 
paints  and  powders?     (Is  a  "white   lie"  more   truthful 
than  a  pink  one  ?) 

A  young  lady  with  a  very  beautiful  complexion  was 
once  asked  the  secret  of  it.  She  said  that  when  she  was 
a  little  girl  she  spent  the  night  with  a  neighbor's  daughter, 
and  they  amused  themselves  dressing  in  the  clothes  of  an 
elder  sister  and  powdering  their  faces.  On  returning 
home  next  morning  from  her  visit,  her  mother  saw  some 
of  the  rice  powder  still  around  her  eyes  and  punished  her 
with  "a  switching,"  and  told  her  that  she  must  never  do  so 
again.  She  never  did,  and  grew  up  with  the  complexion 
of  her  childhood. 


1  The  study  of  physiology  cannot  be  made  practical  without  observing  the 
effects  of  violating  its  laws  in  daily  life.  In  tracing  the  effects  of  tobacco, 
overeating,  alcohol,  ignorant  treatment  of  the  skin,  overwork,  etc.,  it  would 
be  manifestly  improper  and  ill-mannered  to  refer  to  persons  by  name  in  a 
public  place  such  as  a  school. 


THE   SKIN  21 

27.  Review  of  Functions  of  the  Skin.  —  Its  chief  function, 
one  of  more  importance  than  all  others  combined,  is  protec- 
tion of  the  body.    The  dead  outer  cells  well  fit  it  for  this,  as 
does  its  peculiarity  of  becoming  thicker  where  friction  is 
greater.     Savage  man's  only  protection  for  his  head  from 
the  heat  of  the  sun  and  the  blows  of  enemies,  is  his  hair. 

28.  Physiologists  usually  mention  the  absorbing  power  of 
the  skin,  but  this  is  very  slight ;  if  it  were  great,  the  skin 
would  lack  part  of  its  ability  to  protect.     As  it  is,  man  can 
handle  poisons  without  harm,  provided  there  is  no  break  in 
the  epidermis.      He  can  suck  with  safety  the  poison  from  a 
bite  made  by  a  rattlesnake  if  there  is  no  raw  place  or  break 
in  the  mucous  membrane  of  the  mouth.      If  the  poison 
should  be  swallowed,  the  stomach  would  destroy  it.     Some 
volatile  poisons  like  the  poison  ivy  can  penetrate  the  skin. 

29.  Some  writers  mention  the  respiratory  or  breathing 
power  of  the  skin  and  speak  of  the  skin  as  a  third  lung, 
but  this  is  a  great  exaggeration.     The  skin  probably  has 
about  one  fiftieth  of  the  breathing  capacity  of  the  lungs. 
The  pathetic  story  told  concerning  a  child  who  was  gilded 
to  represent  an  angel  in  a  pageant  held  in  honor  of  one 
of  the  popes,  may   be   true.     The  child  is  said  to  have 
died  in  a  few  hours.     Death  was  probably  due  to  some 
poison    absorbed    in    the    process    of   gilding.      A   man 
can  live  after  his  body  is  varnished  or  covered  with    a 
layer  of  impenetrable  substance.     But  varnishing  the  skin 
of   an  animal  covered   with   fur   leads  to  its  death  from 
loss  of  heat,  as  the  varnish  destroys  the  non-conducting 
property  of  the  fur. 

30.  The  skin  is  an  organ  of  sensation,  the  nerve  fibers 
going  not  only  to  the  papillae,  but  some  of  the  finer  fila- 
ments penetrating  even  among  the  deeper  epithelial  cells. 

31.  The  skin  is  an  organ  of  excretion,  the  chief  sub- 
stances excreted  being  water,  salt,  ammonia,  and  a  slight 
trace  of  a  crystalline  solid  called  urea. 


22  ELEMENTS  OF  PHYSIOLOGY 

32.  The  skin  is  the  chief  organ  for  regulating  the  temper- 
ature.    It  accomplishes  this  by  means  of  the  perspiration. 

33.  Clothing  does  not  give  heat  to  the  body,  but  helps 
to  prevent  the  escape  of  bodily  heat.     Linen  and  cotton 
absorb  moisture  readily  and  allow  it  to  evaporate  rapidly. 
They  thus  serve,  when  worn   next  to  the  skin,  to  keep 
the  body  dry ;  the  evaporation,  if  very  rapid,  may  chill  the 
body.     Woolen  absorbs  moisture  quickly,  but  parts  with 
it  slowly,  and  in  the  case  of  those  who  perspire  freely, 
the  damp  clothing  next  to  the  skin   may  conduct   away 
the    heat.      But   dry   woolen   contains   much   air   in   the 
meshes  of  the  cloth ;  and  as  this  is  a  non-conductor  of  heat, 
such  clothing  is  the  warmest  of  all,  silk  ranking  next.     In 
cold  climates  woolen  should  be  worn  next  to  the  skin,  and 
should  not  be  laid  aside  until  the  heat  of  summer  begins. 
In  warm  climates,  like  that  of  the  Gulf  States,  it  should  not 
be  worn  next  to  the  skin  at  all,  even  in  winter,  unless  by 
the  very  delicate,  and  it  is  a  question  as  to  whether  woolen 
does  not  do  more  harm  than  good,  even  to  the  delicate,  as 
it  relaxes  and  weakens  the  skin.     If  it  is  worn  in  such 
climates,  with  the  warmth  of  spring  it  should  be  changed 
for  less  relaxing  fabrics.     White  clothing  reflects  the  heat 
of  the  sun ;  dark  clothing  absorbs  the  sun's  heat.     Rubber 
clothing  prevents  moisture  from  penetrating  to  the  body 
and  also  prevents  perspiration  from  escaping. 

34.  Bathing.  —  A  bath  is  necessary  for  cleanliness,  once 
a  week  in  winter  and  perhaps  daily  in  summer.     Frequent 
bathing,  if  accompanied  by  the  use  of  soap  and  friction, 
makes  the  skin  too  thin   and   sensitive.     A   warm   bath 
should  be  succeeded  by  a  dash  of  cold  water  to  overcome 
its  relaxing  effects.     A  warm  bath  is  more  suitable  on  retir- 
ing than  on  rising ;  it  is  also  more  suitable   than   a   cold 
bath  for  a  person  that  is  much  fatigued.     A  cold  bath  is 
more  invigorating  than  a  warm  bath,  and  should  be  followed 
by  a  reaction  or  glow  caused  by  the  return  of  the  blood  to 


THE  SKIN  23 

the  skin.  The  cold  water  stimulates  the  heart  and  lungs 
and  causes  the  bather  to  breathe  deeply  and  vigorously. 
A  cold  bath,  if  not  taken  rapidly,  may  injure  a  delicate 
person  more  by  its  duration  than  by  its  coldness ;  a  deli- 
cate person  may  bear  a  very  cold  shower-bath  if  continued 
for  only  a  few  seconds. 

35.  THOUGHT  LESSON.  The  Value  of  Health.  —  i. 
Name  five  blessings  in  youth  or  later  in  life  that  result 
from  good  health. 

2.  Name  five  unfortunate  results  of  bad  health. 

3.  Name  five  things  that  people  apparently  value  more 
highly  than  health. 

4.  Think  of  ten  grown  persons  at  random.     How  many 
of  the  ten  are  in  sound  health  ? 

APPLIED   PHYSIOLOGY 
EXERCISE  I 

1.  Why  does  the  palm  of  a  washerwoman's  hand  absorb  more 
water  than  the  back  of  the  hand  ?     (§  11.) 

2.  If  a  hair  is  pulled  out,  what  determines  whether  it  will  grow 
again?    (§9.) 

3.  Why  is  linen  used  for  towels  ?     (§  33.) 

4.  What  causes  the  hair  to  "  stand  on  end  "  when  a  person  is  fright- 
ened or  when  an  animal  is  cold  ?     (§  10.) 

5.  Calculate  the  length  of  the  perspiratory  tubes  in  one  square  inch 
of  the  palm,  if  placed  end  to  end.      (§  7.) 

6.  Why  does  the  skin  become  roughened  and  chapped  in  cold 
weather?     (See  chapter  on  Circulation.) 

7.  What  color  of  clothing  is  best  adapted  to  summer  ?    To  winter  ? 

8.  When  is  a  scar  incapable  of  being  affected  by  freckles  or  tan? 

9.  Could  a  scar  on  a  negro  be  white  ? 

10.  How  may  rubber  shoes  make  the  feet  moist? 

EXERCISE  H 

11.  Why  does  the  heat  seem  more  oppressive  in  moist  weather? 

12.  Which  should  usually  wear  warmer  clothing,  a   farmer  or  a 
merchant  ? 


24  ELEMENTS   OF  PHYSIOLOGY 

13.  Which  teeth  cut  like  a  pair  of  scissors  ? 

14.  Why  is  the  outer  surface  of  leather  smoother  than  the  inner  ? 

15.  How  long  does  it  take  a  spot  of  indelible  ink  on  the  fingers  to 
wear  off  ?     Of  what  does  this  show  the  rate  of  change  ? 

1 6.  How  may  indigestion  cause  the  teeth  to  decay  ? 

17.  In  what  respect  do  patent  leather  shoes  resemble  rubber  shoes  ? 

18.  Why  is  baldness  more  common  among  men  than  among  women  ? 

19.  How  do  you  account  for  the  location  and  shape  of  the  bald  spot  ? 

20.  When  their  skins  contain  the  same  amount  of  pigment,  a  man's 
complexion  is  darker  than  a  woman's,  because  his  blood  is  darker,  since 
it  contains  ten  per  cent  more  red  corpuscles.     Why  do  women  desire  a 
fair  complexion  ? 

21.  Why  is  a  woman's  complexion  considered  beautiful  when  it  is 
pink  and  fair,  but  ugly  when  it  is  pale  or  sallow  ? 

EXERCISE  HI 

22.  Did  you  ever  know  of  a  case  of  loss  of  health  caused  by  chang- 
ing the  warm  clothing  of  daily  wear  for  the  thin  or  scanty  dress  of 
a  ball  or  party  ? 

23.  Why  should  we  remove  an  overcoat  or  a  cloak  when  we  go  into  a 
warm  room  ? 

24.  Why  is  cold  water  better  than  warm  water  for  the  daily  bath  ? 

25.  Should  a  person  wait  for  a  warning  such  as  fatigue,  depression,  or 
chilly  feeling  before  leaving  a  bath  in  the  sea  or  an  ordinary  bath  ? 

26.  Why  do  healthy  persons  living  along  the  Atlantic,  Pacific,   or 
Gulf  coasts,  have  softer  skins  and  fresher,  rosier  complexions  than 
those  who  live  in  the  interior  of  the  United  States?      Why,  if  they 
live  in  forest  regions  such  as  Louisiana  and  east  Texas,  rather  than  in 
prairie  regions  such  as  west  Texas,  Kansas,  and  Nebraska  ? 

27.  Why  are  the  complexions  of  English  people  fresher  and  rosier 
than  those  of  people  in  the  United  States  ? 

28.  Glass  allows  the  radiant  heat  of  the  sun  to  pass  through  ;  wood 
does  not.     Why  are  inside  blinds  appropriate  in  cold  climates  but  very 
unpleasant  and  inappropriate  in  warm  climates  ? 

29.  Which  are  healthier,  and  in  better  taste  for  furniture,  in  the 
Gulf  States  and  the  West  Indies,  willow  and  rattan,  or  plush  and  velvet? 

30.  Show  how  the  wearing  away  of  the  outer  cells  of  the  epidermis 
contributes  to  the  cleanliness  of  the  body. 


CHAPTER   II 
CELLS  AND  TISSUES 

36.  The  Place  of  Physiology  among  the  Natural  Sciences. 
—  Natural  objects  have  long  been  divided  for  purposes  of 
study  into  the  Mineral,  Vegetable,  and  Animal  kingdoms. 
Are  any  two  of  these  divisions   more   closely  related   to 
•each  other  than  they  are  to  the  third  ?     Yes,  we  find  that 
an  animal  and  a  plant  resemble  each  other  and  differ  from 
a  mineral  in  that  they  are  both  alive.     In  order  to  carry  on 
the  mysterious  process  called  life,  animals  and  plants  must 
have  an  orderly  growth  and  activity.     The  parts  by  means 
of  which  they  carry  on  this   activity  are  called  organs ; 
and  plants  and  animals  together  form  what  is  called  the  or- 
ganic kingdom,  while  minerals  form  the  inorganic  kingdom. 

37.  The  science  which  treats  of  living  things  in  general 
is  called  Biology.     Botany  is  one  of  the  biological  sciences 
and  treats  of  plants.     Zoology  is  another  branch  of  biol- 
ogy and  treats  of  animals. 

38.  We  may  study  the  body  of  an  animal  in  two  ways. 
We  may  study  the  structure  and  forms  of  its  organs ;  this 
science  is  called  Anatomy,  and  it  may  be  studied  in  the 
dead  body  better  than  in  the  living  animal.     Or  we  may 
study  the  actions  or  the  functions  of  the  organs  of  the  living 
animal;  this   science  is  called  Physiology.     It  is  divided 
into  Plant  Physiology  and  Animal  Physiology.     Anatomy 
is  likewise  divided  into  two  sciences. 

39.  The  Study   of  the   Human  Body. — The  study  you 
have   undertaken    is    generally,    for    convenience,    called 
Physiology ;  but  Anatomy  must  also  form  a  part  of  the  study, 

25 


26  ELEMENTS  OF  PHYSIOLOGY 

since  we  cannot  understand  the  functions  or  the  actions  of  an 
organ  without  knowing  its  form  and  structure.  But  if  we 
go  no  further  than  these  sciences,  we  may  as  well  be  study- 
ing the  position  of  the  stars  in  the  constellation  of  Orion 
so  far  as  practical  benefit  to  our  lives  is  concerned.  There 
is  a  third  science  based  upon  the  other  two,  called  Hygiene, 
or  the  Science  of  Health.  It  treats  of  the  proper  surround- 
ings for  healthful  living,  and  of  the  activities  of  the  body 
necessary  for  the  perfect  performance  of  all  its  functions. 
It  is  in  Hygiene  that  Anatomy  and  Physiology  find  their 
practical  application. 

40.  The  study  of  the  human  body  should  give  the  follow- 
ing results :  — 

1.  It  should  be  a  means  of  intellectual  training  through 
the  attempt  to   master  its  facts,  solve  its  problems,  and 
comprehend  the  relations  of  its  parts. 

2.  It  should  be  a  source  of  pleasure  in  leading  us  to  real- 
ize the  wonders  of  our  bodily  structure  and  the  wonderful 
adaptations  of  the  body  to  the  surrounding  conditions. 

3.  It  should  give  a  thorough  knowledge  of  one  vertebrate 
animal  that  would  greatly  aid  in  studying  other  animals. 

4.  It  should  give  knowledge  which,  rightly  applied,  would 
form  a  basis  for  intelligent  care  of  the  health.      It  should 
thus  be  a  training  in  "  common  sense,"  which  expression 
taken  in  its  original  meaning  denotes  "sense  about  com- 
mon things."     We  see  why  physiology,  if  studied  thought- 
fully, affords  a  better  training  in  common  sense  than  almost 
any  other  study,  when  we  remember   that   health  is  the 
commonest  of   all  subjects   for  observation   and   conver- 
sation, and  that  every  habit  and  surrounding  condition  of 
life  affects  the  health.1 

41.  Cells. — While    studying   the    skin,    reference   was 
made  a  number  of  times  to  the  cells  of  which  it  is  chiefly 

1  To  a  person  who  is  destitute  of  common  sense,  or  who  fails  to  use  his 
common  sense  while  studying  this  subject,  it  may  become  the  occasion  of 


CELLS  AND    TISSUES  2/ 

composed.  Before  passing  to  the  study  of  any  of  the  in- 
ternal organs,  it  will  be  necessary  to  study  more  thoroughly 
the  nature  of  cells.  The  unit  of  structure  of  animals  and 
of  plants  is  a  minute  object  called  the  cell,  and  each  of  their 
tissues  and  organs  is  composed  of  many  cells.  The  living 
substance  of  which  the  cell  is  made  is  called  protoplasm 1 
and  this  name  is  applied  to  the  cell  substance  of  both 
animals  and  plants.  Workers  with  the  microscope  over 
a  century  ago  found  that  plant  and  animal  tissues  are 
composed  of  little  chambers,  which  they  called  cells.  It 
was  found  later  that  the  liquid  in  the  little  chambers  is  of 
more  importance  than  the  walls  which  the  protoplasm 
builds  around  itself.  The  wall  was  first  called  a  cell; 
now  we  use  the  word  cell  for  the  globule  of  living  proto- 
plasm together  with  its  wall,  if  it  has  one. 

42.  Protoplasm.  —  We  should  not  think  because  we  use 
the  same  name,  protoplasm,  for  the  substance  forming  the 
cellular  material  of  both  animals  and  plants,  that  its 
chemical  composition  is  always  exactly  the  same.  This 
varies  in  different  cells,  and  is  indeed  so  complex  that 
no  chemist  has  ever  been  able  to  analyze  it.  The  proba- 
bility is  that  it  will  never  be  analyzed,  as  its  complexity 
seems  unlimited.  Besides,  there  is  no  such  thing  as  dead 
protoplasm.  As  soon  as  a  chemist  begins  to  analyze 
protoplasm,  it  separates  into  a  number  of  substances.  It  is 
transparent  and  jelly  like,  yet  under  a  microscope  there 

many  unreasonable  and  misleading  notions.  This  is  especially  the  case  with 
extremists,  or  with  persons  who  entertain  only  one  idea  at  a  time.  They  are 
unable  to  assign  to  each  truth  its  proportionate  importance. 

These  are  the  persons  who  chill  themselves  in  order  to  ventilate,  worry 
themselves  about  digestion,  make  themselves  nervous  while  trying  to  develop 
their  muscles,  etc.  On  the  other  hand,  we  all  know  of  eases  where  a  person 
when  young  was  the  weakest  member  of  the  family;  but  who,  through  an  intel- 
ligent study  of  physiology  and  hygiene,  became  the  soundest  and  healthiest 
one  in  the  family,  and  outlived  those  who  were  at  first  sound  and  strong. 
1  Greek, protos,  first;  plasma,  that  which  is  molded. 


28 


ELEMENTS   OF  PHYSIOLOGY 


V 


appears  an  interlacing  series  of  beads  and  lines  (Fig. 
26).  But  there  must  be  some  test  for  identifying  pro- 
toplasm, or  we  should  never  be  able  to  tell  organic  from 
inorganic  matter ;  animal  and  plant  substance  from 
mineral.  The  only  distinguishing  feature  yet  known 
about  protoplasm  is  that  there  are  always  found  in  it 
certain  complex  albuminous  substances  that  are  never 
found  in  inorganic  bodies.  The  white  of  an  egg,  also 
called  albumen,  is  such  a  substance. 
The  power  that  the  cells  possess  of  per- 
forming the  processes  of  life  depends 
upon  the  presence  of  these  albuminous 
substances.  The  albumin,  or  nitroge- 
nous substance,  in  protoplasm  makes  it, 
therefore,  the  life  substance,  and  dis- 
tinguishes it  from  the  mineral  world. 
Nothing  in  the  world  besides  animals 
and  plants  possesses  the  power  of 
growth  by  converting  other  material 
into  its  own  kind  of  substance. 

43.  Difference   between  Animals  and 


'"Water 


FIG.  24.  —  Diagram. 


The  plant  taking  in  carbonic 

acid  gas,  called  also  car-  Plants.  —  Can  you  always  tell  an  animal 

bon  dioxid,  the  product  of    ^ n     ^ ^  ? 


fire  and  of  animal  life.    By 


from  a  plant  ?     You  say  an  animal  can 


means  of  the  sun's  energy     mQve   from   pjace    to    place  ;    the    TCply  is, 
the  leaf  builds  the  carbon 

into  living  forms  and  gives  no,  a  sponge  and   many  other  animals 

back  the  oxygen  to  the  air.  .          .    , 

cannot.  You  say  an  animal  has  nerves 
and  feeling,  but  some  simple  animals  are  without  nerves  ; 
on  the  other  hand,  some  plants  respond  to  a  stimulus  or 
irritation,  although  they  never  develop  special  organs 
for  transmitting  the  stimulus.  It  is  easy  to  distinguish  the 
higher  animals  from  plants  ;  but  in  regard  to  many  of  the 
lowest  forms  of  single-celled  organisms,  the  most  learned 
biologists  find  it  impossible  to  say  whether  they  are  plants 
or  animals.  The  clearest  difference  between  animals  and 
plants  is,  that  plants  get  their  food  directly  from  mineral 


CELLS  AND    TISSUES 


29 


substances,  while  animals  must  get  their  food  from  organic 
substances,  either  from  plants  or  from  other  animals  which 
in  turn  have  eaten  plants.  The  plant  builds  up  complex, 
unstable  substances  by  means  of  the  sun's 
light  and  heat  (Fig.  24).  The  animal  eats 
the  plant,  and  these  substances  are  finally 
reduced  in  the  body  to  simple,  stable  sub- 
stances, thus  setting  free  the  energy  stored 
up  in  the  plant.  (What  is  it,  therefore, 
that  indirectly  furnishes  the  energy  that  FIG.  25.  —  Diagram  of 

..  ,./    5X  the  Parts  of  a  Cell. 

sustains  all  life  ? ) 

44.  A  Living  Cell  has  two  essential  parts :  a  small  mass 
or  globule  of  protoplasm,  and  a  still 
smaller  body  in  its  interior,  also  consist- 
ing of  protoplasm,  called  a  nucleus  (Fig. 
25).  There  may  be  two  other  parts,  for 
often  there  is  a  still  smaller  body,  a  dot 
in  the  nucleus,  called  a  nucleolus,  and 
usually  the  protoplasm  has  a  wall  sur- 
rounding it  called  the  cell  wall  (Fig. 
26).  Cells  are  of  various  shapes  and 

showing  that  protoplasm  has  constitute  the  substance  of  all  the  or- 

an    intricate  structure;    in 

this  case  it  appears  some-  gans.      The  cells  are  all  of  the  human 

what  like    honeycomb;   /,«,.«.«  •,-,         -,.  ,,  -, 

protoplasm ;  n,  nucleus ;  body  that  is  really  alive,  the  substances 
in  the  body  outside  of  cells  not  being 
considered  living  matter.     A  cell  may  be  defined  as  a  tiny 
particle  of  protoplasm  containing  a  nucleus. 


FIG.  26.  —  Diagram  of 
a  Cell. 


FIG.  27.  —  A  Cell  that  is  Slender  and  in  the  Form  of  a  Fiber. 
It  is  from  the  muscular  coat  of  the  intestines  ;  /,  granular  protoplasm  around  the  nucleus,  n. 

45.  Fibers. — In  some  of  the  tissues  the  cells  are  very 
long  and  slender,  and  a  single  cell  forms  a  fiber.  A  fiber  is 
stringlike  in  shape  (Fig.  27).  Sometimes  the  fibers  consist 
of  rows  of  cells  or  of  long,  fine  branches  of  cells. 


ELEMENTS   OF  PHYSIOLOGY 


FIG.  28. —  Cells  forming  a  Membrane. 

(Mucous  membrane  of   intestines.)     A  few    cells   (dark)    that    from 
secrete  mucus  are  shown. 


46.   Membranes.  —  Sometimes  the  cells  lie  side  by  side, 
packed  closely  together,  and  form  a  thin  skinlike  structure, 

called  a  mem- 
brane (Fig.  28). 
47.  The  Varied 
Life  of  the  Cells. 
—  Some  cells,  as 
the  red  blood 
cells,  move  about 
place  to 
place,  but  always 
keep  in  a  definite  channel.  There  is,  however,  one  kind  of 
cell,  called  the  white  blood  cell,  that  can  change  shape  and 
pass  from  one  tissue  into  another  (Fig.  29). 

48.  In  having  a  wall,  soft  contents,  and  nucleus,  the  cells 
of  the  body  resemble  minute  one-celled  animals  sometimes 
found  in  water.  Figure  30  shows  the  appearance  under 
the  microscope  of  the  ameba,  one  of  these  small  animals. 
The  ameba  seems  to  be  hardly  more  than  a  minute  drop  of 
jelly,  yet  it  can  move  by  pushing  out  a  part  of  its  body. 
It  can  absorb  food  from  a  tiny  particle  by  rolling  itself 
around  the  par- 
ticle (Fig.  30). 
Afterward  the 
ameba  pulls  it- 
self away  and 
leaves  behind  the 
indigestible  part. 
If  the  ameba  is  jarred  or  struck,  it  shows  that  it  has  feeling. 
It  absorbs  oxygen  and  gives  off  carbon  dioxid.  When  it 
attains  a  certain  size,  it  divides  into  two  parts,  which  lead 
independent  lives  (Fig.  31).  The  white  blood  cells  are 
more  like  independent  one-celled  animals  than  any  of  the 
other  cells.  Some  animals  are  larger  than  others  because 
their  bodies  contain  more  cells,  not  larger  cells. 


FlG.  29. —  Successive  Forms  assumed  by  a  Colorless 

Corpuscle  of  the  Human  Blood. 

At  intervals  of  one  minute. 


CELLS  AND    TISSUES 


49.  An  Ordinary  Animal  is  a  Community  or  Colony  of 
Cells.  —  An  animal  such  as  a  horse  or  a  man,  made  up  of 
millions  of  cells,  may  be  compared  to  a  colony 
or  community  of  one-celled  animals.  When 
a  child  is  born  in  a  community  of  people,  we 
cannot  tell  what  part  in  the 
community  it  is  destined  to  fill. 
When  a  new  cell  is  formed  in 
the  body,  by  the  division  of  an 
old  cell  into  two  cells,  it  may 
serve  its  community  as  a  rail- 
road man  serves  a  community 
of  people,  that  is,  as  a  red  blood 
cell,  and  carry  food  from  place 
to  place  ;  or  it  may  be  a  farmer 
cell,  that  is,  a  digestive  cell,  and 
convert  crude  material  into  sub- 
stances ready  for  use  by  the 
other  cells.  It  may  be  a  senti- 
nel and  soldier,  that  is,  a  white 
blood  cell,  and  go  to  any  place 
that  is  attacked  by  foreign  or- 
ganisms, such  as  microbes,  or  it 
may  help  to  repair  a  break  in  the 
wall,  as  when  the  white  blood 
cells  (a  kind  of  "jack  at  all 
FIG  QO—  The  trades")  collect  in  great  numbers 


FlG   3I  _ 
undergoing  Di- 


Ameba  (as  ancj  form  the  white  matter  seen 

seen  under  a 


the  pro- 
cess are  shown. 
The  nucleus  di- 
vides as  well  as  the 
rest  of  the  cell.  The 


,       <          .  i  r\        i  rest  01  iiicL.cn.   xiic 

high  power  of  around  a  cut  in  the  flesh,  or  a     mother  cell  divides 
the  micro-  sore  that  is  healing.     It  may  be     in'°  two  daushter 

scope)  taking  /  cells. 

food.  a  carpenter  cell,  that  is,  a  bone 

cell,  and  help  to  form  the  framework  or  skeleton  of  the 
great  house  which  shelters  the  community ;  and  last  of 
all,  it  may  be  a  director  and  guide  for^the  community, 
that  is,  one  of  the  nerve  cells,  which  correspond  to  the 


32  ELEMENTS   OF  PHYSIOLOGY 

officiate,  teachers,  and  preachers  of  any  ordinary  community 
of  human  beings.  One  man  learns  to  do  one  kind  of  work 
and  can  do  this  better  than  anything  else.  Often  the 
nature  of  his  work  can  be  judged  by  his  appearance:  so 
it  is  with  the  cells.  Still,  the  general  structure  of  all 
cells  is  essentially  the  same,  just  as  all  men  are  alike  in 
their  plan  of  structure.  Thus  the  tissues  of  the  higher 
animals  beautifully  exemplify  the  principle  called  — 

50.  Division  of  Labor.  —  By  this  means  a  community  of 
men  working  together  can   accomplish  vastly  more  than 
the  same  number  working  separately.     Each,  learning  to 
do  a  few  things  well,  can  turn  out  perfect  products  of 
skilled  labor,  and  by  a  system  of  interchange  can  come  to 
possess  the  products  of  the  skilled  labor  of  others.     With- 
out this  the  human  race  could  have  made  but  very  little 
progress  and  would  have  remained  in  the  state  of  savages, 
who  do   not   practice  the  division  of  labor  to  any  great 
extent. 

51.  In   the  human   body,  the  several   groups  of  cells 
called  tissues  have  divided  among  themselves  the  various 
physiological  processes  :   the  muscle   cells   are  for  move- 
ment, nerve  cells  for  feeling,  gland  cells  for  digestion,  etc. 
They  are  thus  unlike  the  ameba,  whose  one  cell  carries  on 
all  the  functions,  unaided  by  any  other  cell.     Still,  in  the 
body  of  a  higher  animal,  each   cell  has  many  forms  of 
activity  common  to  the  ameba  and  all  other  living  cells; 
it  requires  food  as  much  as  if  it  lived  alone,  and  its  food 
is  digested  and  brought  to  it  in  a  state  ready  for  use ;  it 
requires  oxygen,  and  the  oxygen  is  separated  by  special 
cells  and  brought  to  it  purer  than  that  found  in  air  or 
water.     Cells  all  have  at  least  sometime  in  their  lives  the 
power  to  increase  in  size,  and  to  reproduce  themselves  by 
dividing  just  as  the  ameba  does  (Fig.  31).     In  this  way,  the 
tissues  grow,  and  thus   they  may  be   repaired  if   injured 
or  broken. 


CELLS  AND    TISSUES  33 

52.  The  Tissues.  —  Sets  of  similar  cells  are  grouped  to- 
gether to   form   tissues.      The    cells    may   develop    long 
branches,  called  processes  or  fibers,  and  may  deposit  mate- 
rial between  adjoining  cells  called  intercellular  substance. 
A   tissue   consists    of    a  mass  of   cells  built  up  together, 
along  with  all  of  their  processes  and  intercellular  substance. 
A  part  of  the  body  which  has  a  definite  work  to  do  is  called 
an  organ,  and  each  organ  consists  of  several  tissues.     The 
tissues  are  of  many  kinds.     In  order  to  understand  them 
clearly  and  to  remember  them  distinctly,  we  must  learn 
them  according  to  their  uses  in  the  different  organs. 

53.  What  are  the  chief  uses  or  purposes  of  our  bodies  ? 
If  we  consider  our  life,  we  shall  at  once  say  that  our  bodies 
enable  us  to  perceive,  to  feel,  to  think,  on  the  one  hand, 
and  to  work,  to  execute,  to   exert  energy,  on  the  other. 
The  powers  of  thinking  and  doing  have  two  tissues  allotted 
to  them  in  the  animal  economy,  and  these  two  tissues  have 
been   named   by  physiologists,  the   master  tissues,  while 
the  remaining  tissues,  to  which  are  intrusted  the  protec- 
tion, support,  and  renewal  of  the  master  tissues,  are  called 
the  supporting  tissues.     The  two  master  tissues,  or  those 
that  have  to  do  with  controlling  and  exerting  energy,  are 
called,  respectively,  the  muscular  and  the  nervous  tissues. 
They  will  be  treated  in  a  general  way  in  the  next  chap- 
ter, so  that  their  part  in  the  functional  activity  of  each  of 
the  various  organs  may  be  understood  as  they  are  taken 
up  in  turn.     Those  organs  the  chief  functions  of  which 
are  nervous  or  muscular  will  be  studied  in  later  chapters. 

54.  In  studying  the  definitions  of   the  tissues  and  the 
drawings  showing  microscopic  views  of  them,  it  will  be 
well  to  remember  that  they  are  all  developed  from  the 
same  elements,  namely,  nucleated  cells.     Every  tissue  in 
the  earlier  stages  is  a  mass  of  such  cells  packed  together. 
The  cells  of  one  tissue,  when  mature,  resemble  one  another, 
but  are  unlike  those  of  other  tissues. 


CHAPTER   III 


THE  SUPPORTING  TISSUES 

55.  Connective  Tissue  consists  of  three  elements :  white 
fibers,    yellow    fibers,    and    connective  tissue    cells.      The 
white  fibers  (Fig.  32)  are  not  elastic.     They  form  a  mesh- 
work  of  bundles  running  in  various  directions.     The  bun- 
dles   consist    of    still 
smaller    fibers   which 
are    fine,    long,    and 
wavy;  they  run   par- 
allel   in    the    bundle 
and   never    branch. 
Scattered  among  the 
bundles    are    some 
branching      fibers, 
forming    a    network ; 
they  are   yellow   and 
generally      much 
thicker  than  the  white 
fibers,  and  are  called 
yellow    elastic  fibers. 

They  form  the  second  element  in  connective  tissue  (Fig. 
32,  c).  The  third  element  is  the  connective  tissue  cells. 
They  are  scattered  among  the  fibers.  Each  has  a  nucleus 
(Fig-  33)  >  many  of  them  are  much  branched  and  the 
fibrous  parts  ®f  the  tissue  already  described  are  believed 
to  have  been  first  formed  as  branches  of  such  cells. 

56.  This   wonderfully   strong,    though    delicate,    tissue 
(Fig.    34)  is  found  in  every  organ,  binding   together  and 
holding  in  place  the  various  tissues  and  cells,  thus  pre- 
34 


FIG.  32.  —  Connective  Tissue  Fibers. 

a,  small  bundles  of  white  fibrous  tissue;   b,  larger 
bundles;  c,  single  yellow  elastic  fibers. 


THE   SUPPORTING    TISSUES 


35 


serving  delicate  tissues  like  the  master  tissues  from  strain 
and   injury.     It  is  said   that  if   every  other  tissue  were 

removed,  the  connective  tis- 
sue would  still  give  a  perfect 
model  of  all  the  organs.  The 
tendons  and  ligaments  consist 
almost  wholly  of  it.  Leather, 
the  part  of  skins  that  is  left 
after  tanning,  is  made  up  of 
connective  tissue.  You  have 

FIG.  33- -Connective   Tissue   Cor-     already    leamed    ^    the    ^ 
c,  cell;  A  process  ;  n,  nucleus.  skin    Consists    of    nerVCS,    blood 

vessels,  and  glands  supported 

by  fibers  of  connective  tissue.     In  tanning,  the  more  deli- 
cate parts  are  destroyed  and  only  connective  tissue  is  left. 

57.  Adipose  (Fatty)  Tissue.  —  This  soft  tissue  furnishes 
cushions  for  delicate  organs  like  the  eye,  forms  a  layer 
under  the  skin,  thus  rounding 

out  the  form,  and  storing  up 
food  for  the  use  of  nerve,  mus- 
cle, and  other  cells.  The  fat  6~ 
is  first  deposited  in  the  form  of 
minute  globules  in  the  connec- 
tive tissue  corpuscles,  or  cells ; 
these  globules  gradually  in- 
crease in  size.  That  fatty  tissue 
consists  of  both  cells  and  fibers 

,    .       ,          .  .    -  FIG.  34.  —  Connective  Tissue. 

and  is  developed  from  connec-  ,   , 

a,   fibers  with   cells   on   them  ;    b,   free 

tlVe  tissue  Can  be  Seen  by  Study-         cells  in  spaces  ;  c,  yellow  elastic  fiber  ; 
T^-  o         T>I          r    *     •  d>  blood  capillary. 

ing  Figure   38.     The  fat  is  in 

the  cells,  and  the  cells  are  lodged  in  pockets  formed  by 

meshes  of  the  fibers  of  connective  tissue. 

58.  What  part  of  the  tissue  of  hog  fat  furnishes  lard  ? 
What  does  beef   fat  contain   that   is    not  in  the  tallow? 
What  is  suet  ? 


ELEMENTS   OF  PHYSIOLOGY 


59.  Epithelial  Tissue.  —  Covering  the  surface  of  the 
body  and  lining  every  cavity  and  tube  of  its  interior,  is  a 
tissue  consisting  of  one  or  more  layers  of  dis- 
tinct cells,  forming  what  is  called  epithelial 
tissue.  You  learned  in  Chapter  I  that  from 
it  the  hair  and  nails  are  produced.  It  is  per- 

haps the  simplest  of 
the  tissues,  consist- 
ing merely  of  cells 
packed  closely  to- 
gether, and  united  by 
a  very  small  amount 
of  a  cement  sub- 
stance of  albuminous 
nature.  The  cells 
may  be  in  a  single  FlG'|^~The 
layer,  as  in  the  mu-  Epithelial  ^  at 
cous  membrane  of  <A  and  *  •  con- 

nective  and  fatty 

the    intestine    (Fig. 
28),  or  in  many  lay- 

FlG.    35.  —  Connective  or  Sup-  .          •  • 

porting  Tissue  taken  from  be-    ers,     as    in     the    epl- 

neath  the  skin.  dermis.      No    blood 

Notice  that  there  is  a  loose  network  ,  •**.!. 

of   wavy    bundles  of  fibers,    also  VCSSClS  paSS    HltO  tilC 

a    network    of    threadlike     fibers^  epithelial  tisSUC  J    the 
These  fibers  were  probably  formed 

by  the  cells  which  you   see  lying  cells        derive        their 
in  the  meshes. 

nourishment  by  ab- 

sorbing it  from  the  watery  portion  of  the 
blood  exuded  into  the  adjacent  tissues.  The 
epithelial  tissue  grows  by  subdivision  of  the 
cells  of  the  lowest  layer.  When  the  nu- 
cleus has  disappeared,  the  cells  die  and 
flatten  and  become  mere  horny  plates,  easily 
detached;  and  thus  the  outer  cells  are  con- 


tissue  below. 


FIG.  37.  —  Con- 
nective Tissue. 
(//),  Epithelial. 
(7),intheWall 
of  the  Eyeball. 


stantly  wearing  away  as  you  learned  when  studying  the 
skin. 


THE  SUPPORTING    TISSUES 


37 


60.  The  epithelial  structures  may  be  placed  according 
to  their  functions,  in  two  divisions.     One  is  chiefly  protec- 
tive in  character ;  such  as  the  outer  skin,  the  lining  of  the 
mouth  and  windpipe,  the  epithelial  layers  protecting  the 
delicate  nerves  and  blood  vessels  beneath.    The  other  kind 
of  epithelial  tis- 
sue consists  of 

cells  that  con- 
tain highly 
active  proto- 
plasm and  are 
actively  en- 
gaged in  form- 
ing fluids  called 
secretions,  from 
food  brought 
to  them  by  the 
blood  (Figs,  ii 
to  17).  Such 
are  the  cells  of 
the  salivary 
glands,  which 
secrete  the 
saliva  (Fig. 
40);  of  the 
gastric  glands, 
which  secrete 
gastric  juice 

(Fig.  41  );  of  the  pancreas,  sweat  glands,  kidneys,  liver, 
etc.  This  class  of  epithelial  tissue  is,  therefore,  of  the 
greatest  value  in  purifying  the  body  and  in  preparing 
material  to  be  used  in  its  activities:  it  is  essential  to  the 
growth  of  sound  and  well-nourished  nerve  and  muscle. 

61.  Cartilaginous   Tissue.  —  Some   parts    of   the   body 
require  tissue  having  something  of  the  rigidity  of  bones, 


FIG.  38.  —  Fatty  Tissue. 


ve  ^at  ce^s>  ^e^  together  by  bundles  of  connective  tissue  f\  m, 
the  membrane  or  envelope  of  the  fat  cell ;  n,  the  nucleus,  and  p, 
remains  of  the  protoplasm  pushed  aside  by  large  oil  drop  a. 
Magnified  200  diameters. 


ELEMENTS   OF  PHYSIOLOGY 


yet  capable  of  bending  under  pressure.  This  purpose 
is  fulfilled  by  the  elastic  tissue  called  cartilage.  A  piece 
obtained  fresh  from  the  animal  is  seen  to  be  covered  by  a 
thin  fibrous  membrane,  which  is  reddish  because  it  contains 
blood  vessels.  When  this  membrane  is  stripped  off,  the 

cartilage  shows  no  signs  of  red- 
ness, that  is,  it  contains  no  blood 
vessels.  A  thin  section  of  fresh 
cartilage  appears  to  the  unaided 
eye  as  uniform  as  a  piece  of 
glass.  Under  the  microscope 
we  see  that  it  is  not  so,  but  that 
scattered  in  its  gen- 
eral substance  are  nu- 


FIG.  39.  - 


Lining 


cell  is  rounded  and 
nucleated  (Fig.  43).     They  are  often  in  pairs, 

and  in  that  case  adjacent  sides  are  flat  ;  which 

.      . 
at  once  suggests  that  they  have    ciandCeiis. 

been   formed   by  the  division  of  Resting,  fuii  of 

granules,  after 
activity  ;  lower 


FiG."  40.  — Six 


one  cell.     In  the  growth  of   car-     granules>  after 


tilage  each  cell  divides  into   two     cel,ls  shrunk 

0  and     contain- 

cells.     These  new  cells  later  on     ing  few  gran- 
divide  in   a  similar  way,  so   that 
a  group   of    four    or   eight  cells   that   have 
all  sprung  from  one  cell  may  be  seen.     The 
general   substance   between  the  cells  is  de- 
FIG      i  —TWO  Positecl  by  the  cells  and  is  called  the  inter- 
Gastric  Glands,    cellular  substance  or  the  matrix. 
simple  tubular       gg.    Cartilage  may   be  readily  felt  in  the 

glands    such     as  J  J 

these    may    be  nose  (in  what  portion  ?),  ears,  and  windpipe. 


ifa   It  may  contain  an  abundance  of  the  yellow 
r    °f  th°  elastic  fibers  of  connective  tissue,  in  which 
case  it  is  very  elastic,  as  in  the  ear  ;    or  it 
may  have  masses  of  white  fibers,  and  may  be  unusually 


THE  SUPPORTING    TISSUES 


39 


connective  tissue  cells  and  blood      COlttDOSCd.     of 
vessels.  ^ 


tough,  as  in  the  cartilages  between  the   divisions  of   the 
vertebral  column. 

63.  Osseous  (Bony)  Tissue. — Just  as  ordinary  connective 
tissue  supports  and  holds  in  place  the  delicate  cells  and 

fibers  of  the  organs,  so  the  bone 
and  cartilage  support  the  various 
complete  organs  and  hold  them  in 
their  proper  places  in  relation  to 
one  another.  Cartilage  and  bone 
are  closely  related  as  to  location 
and  function  ;  they  are  also  closely 
related  in  their  development.  For 
FIG.  42.  — Ciliated  Epithelial  example,  in  infancy  the  flat  bones 

Cells,    which    line    the    Air     r  .  ,,  r          j       -j  r    j_i_ 

Tubes.    (Cilia  are  hairiike.)    forming  the  roof  and  sides  of  the 
a,  large  cells;  b,  young  ceils;,,    skull   are  soft   and   flexible,  being 

cartilage,  except  a 
patch  of  bone  in  the  middle  of  each. 
As  growth  proceeds,  the  bones  touch  and  interlock,  replac- 
ing the  cartilage.  If  a  bone  is  broken,  the  new  bone,  as  it 
heals,  is  first  cartilaginous  and  afterward  solid.  Late  in  life 
some  of  the  ordinary  cartilages  of  the  joints  change  to  bone. 

64.  Periosteum.  —  A  bone  usually  has  its  ends  coated  by 
a  layer  of  cartilage.    At 

the  margin  of  the  sur- 
face that  forms  the  joint 
the  cartilage  thins  out, 
and  a  layer  of  vascular 
("full  of  vessels'")  con- 
nective tissue  begins 
and,  extending  over  the 
remaining  surface  of 
the  bone,  forms  a  cover- 
ing for  it,  called  the 
periosteum.  This  con- 
tains the  blood  vessels  which  pass  into  the  bone  to  supply 


FIG. 43.  —  Cartilage.    A  thin  Section,  highly 
magnified. 

m,  matrix ;  a,  group  of  two  cartilage  cells;  b,  a  group 
of  four  cells  ;  c ,  a  cell ;  «,  nucleus. 


40 


ELEMENTS   OF  PHYSIOLOGY 


nourishment.  It  is  closely  adherent  to  the  bone  and  may  be 
removed  by  scraping.  It  is  sometimes  seen  as  a  ragged 
margin  on  the  sawed  end  of  a  bone  fresh  from  the  butcher. 
65.  The  hardest  and  most  compact  part  of  a  bone  seen 
under  the  microscope  shows  the  following  system  of  open- 
ings (Fig.  44):  (i)  canals,  called  Haversian  canals,  run- 
ning lengthwise  of  the  bone  and  containing  blood  vessels 

which  extend  into  them 
from  the  periosteum ; 
(2)  irregular  spaces  called 
lacuna  arranged  in  cir- 
cular lines  around  the 
canals;  (3")  from  the  la- 
cunae numerous  minute 
wavy  passages  called 
canaliculi  pass  inward 
to  the  Haversian  canals, 
while  others  pass  out- 
ward to  open  into  the 
lacunas  in  the  outer  cir- 
cles. The  canaliculi 

afford  PassaSe  to  minute 
blood  vessels. 

66.  The  lacunae  con- 
tain small  cells  called 
bone  cells,  each  having  a 
nucleus  and  sending  out 
fine  processes  or  branches 

for  some  distance  along  the  canaliculi.  They  receive  their 
nourishment  from  the  blood  flowing  through  the  Haversian 
canals,  which  penetrate  to  them  in  their  stony  prisons, 
through  the  canaliculi.  They  have  for  their  special  form 
of  activity  the  building  of  walls  of  phosphate  and  carbonate 
of  lime  about  themselves.  The  walls  built  by  the  neigh- 
boring cells  touch  one  another,  and  becoming  fused  together 


FIG.  44.  —  Bone  cut  across,  highly 
magnified. 

H,  Haversian  canals  ;  /,  lacunae,  connected  by 
canaliculi. 


THE   SUPPORTING   TISSUES  41 

make  the  whole  bone  strong  and  rigid.  Thus  the  hard,  min- 
eral part  of  the  bone  is  deposited  by  these  bone  cells  and  is 
nourished  by  them.  The  bone  corpuscles,  we  thus  see,  lie 
in  the  intercellular  substance  or  matrix,  in  much  the  same 
way  that  the  cartilage  cells  lie  in  the  intercellular  substance 
of  the  cartilage.  In  bone  the  matrix  consists  mostly  of  lime. 

67.  Aided   by  the  figures,  make  a  series  of   drawings 
showing  the  form  of  the  cell  in  the  several  tissues.     Can 
you  see  that  the  cell  has  not  only  similar  parts  but  also 
similar  functions,  in  each  of  the  tissues  studied  ?      Some 
cells  live  only  a  few  hours ;  others,  as  the  cells  of  cartilage 
and  bone,  may  live  for  years. 

68.  It  should  be  repeated  that  each  organ  of  the  body 
consists  not  of  one,  but  of  several  tissues.     The  heart,  for 
example,  is  composed  principally  of  muscular,  nervous,  con- 
nective, and  fatty  tissues ;  the  eye  is  formed  of  nervous, 
connective,  muscular,  and  epithelial  tissues.    The  following 
list  shows  the  several  classes  of  tissues :  — 

MASTER  TISSUES  (  N;™ous  Tissues 
[  Muscular  Tissues 

(  Connective  Tissues 

Fatty  Tissues 
SUPPORTING  TISSUES  J  Cartilaginous  Tissues 

Osseous  Tissues 
^  Epithelial  Tissues 

69.  Tissue  Building.  —  As  you  have  learned,  all  of  the 
tissues  are  built,  maintained,  and  repaired  by  living  cells. 
Life  and  health  depend  upon  the  proper  and  continuous 
activity  of   these  cells,  and  anything  which   aids  in  this 
activity   strengthens   the   body   and    prolongs   life;    any- 
thing which  injures  them  or  interferes  with  their  activity, 
impairs  the  health  and  shortens  life.     Growth  and  repair 
of  tissue  are  promoted  by  sunshine,  by  fresh  air,  by  drinking 
plenty  of  pure  water,  by  good  food,  by  active  and  happy 
occupation.      Weakness    and    injury   of   cell    and    tissue 


42  ELEMENTS   OF  PHYSIOLOGY 

result  from  depriving  the  body  of  these  conditions.  The 
only  possible  way  to  return  to  health  of  the  body  is  to 
restore  these  conditions,  and  adapt  the  daily  life  to  them. 
The  effect  of  various  substances  upon  living  cells  may  be 
watched  under  a  microscope.  If  bathed  with  a  proper 
food  substance,  the  cell  is  seen  to  expand  and  grow  and 
move  more  actively.  If  bathed  in  an  astringent  substance 
like  the  tannin  of  tea,  it  shrinks  and  ceases  its  movements 
until  revived.  If  bathed  in  a  liquid  to  which  a  small  quan- 
tity of  alcohol  has  been  added,  its  activity  ceases,  and 
unless  the  proportion  is  very  small,  such  activity  cannot 
be  restored.  The  chemical  substances  that  actually  attack 
delicate  living  cells,  causing  them  to  shrivel,  or  decompos- 
ing and  destroying  them,  are  called  poisons.  Arsenic  de- 
stroys the  red  blood  cells.  Strychnine  attacks  some  of  the 
master  cells,  namely,  the  nerve  cells,  and  their  activity  in 
attempting  to  cast  off  the  poison  sometimes  throws  the 
body  into  a  spasm.  The  action  of  some  poisons  upon 
cells,  especially  the  nerve  cells,  is  called  — 

70.  Stimulation.  —  This  unnatural  and  exhausting  ac- 
tivity of  the  cells  in  their  efforts  to  free  themselves  from 
poison,  is  interpreted  by  some  persons  to  mean  that  the 
poison  gives  the  strength  and  activity  shown  in  the  cells. 
The  poison  does  not  put  strength  into  the  cells,  but  gets 
it  out,  and  honest  food  alone  puts  the  strength  back. 
Alcohol  hastens  the  breaking  down  of  cell  protoplasm 
and  lessens  the  activity  of  the  tissue-building  cells.  This 
is  one  reason  why  a  person  who  has  been  used  to  alcoholic 
drinks  recovers  less  rapidly  from  an  accident  or  surgical 
operation  than  one  who  uses  none.  One  of  the  first  ques- 
tions asked  by  a  surgeon  before  operating,  is  whether  the 
patient  uses  alcohol.  Tobacco  also  lessens  the  activity 
of  the  cells  that  build  and  repair  the  tissues.  This  is  the 
reason  why  men  who  begin  the  use  of  tobacco  when  young 
boys  are  often  poorly  developed  and  stunted  in  growth. 


THE   SUPPORTING    TISSUES  43 

Opium  completely  paralyzes  certain  cells.  Those  poisons 
which  are  used  by  physicians  to  regulate  the  activity  of  the 
cells  are  called  — 

71.  Drugs  and  Stimulants.  —  There  are  some  people  who 
are  so  reckless  in  regard  to  that  delicate  organism,  the 
body,  that  they  are  ready  to  take  the  place  of  a  physician 
and  to  doctor  themselves  or  their  friends  with  virulent 
drugs  and  patent  medicines,  and  even  to  make  a  habit  of 
using  alcohol,  tobacco,  or  opium.  The  persons  who  pre- 
scribe drugs  to  their  families  or  friends  may  say  they  have 
often  taken  calomel,  quinine,  patent  cure-alls,  headache 
medicines,  etc.,  and  have  not  been  injured.  In  the  case 
of  some  drugs,  the  most  powerful  microscope  may  fail  to 
show  any  effect  upon  the  cells;  nevertheless,  we  know  a 
change  has  occurred,  for  it  requires  more  of  the  same  drug 
to  have  a  like  effect  next  time.  The  wisest  physician  can- 
not peep  into  the  secrets  of  the  cells  and  always  discern 
whether  they  are  injured.  How  presumptuous  in  those 
who  are  not  physicians  to  tamper  with  drugs !  Such  per- 
sons err  through  ignorance  or  presumption  and  often  do 
injury  to  themselves  or  their  dear  ones  which  lasts  through 
life.  The  best  physicians  give  little  medicine,  especially 
when  practicing  in  families  of  intelligent  people  who  have 
the  ability  and  patience  to  carry  out  their  hygienic  direc- 
tions. The  safe  way  is  to  seek  the  conditions  of  life  named 
above.  How  to  do  this  will  be  considered  in  the  sections  of 
this  book  devoted  to  hygiene.  Sickness  is  sometimes  un- 
avoidable. When  a  person  is  in  bed,  it  is  too  late  for  him 
to  cure  himself  by  right  living  alone ;  care  should  be  taken 
to  call  a  good  physician,  and  his  directions  should  be  im- 
plicitly followed.  Self  drugging  by  the  public  is  considered 
by  some  the  most  fruitful  cause  of  disease  in  the  United 
States.  "  Mind  cure  "  and  kindred  ideas  often  do  more  by 
rescuing  victims  from  poisonous  drugs  than  through  their 
calming  effect  upon  the  mind. 


CHAPTER   IV 

THE   MASTER   TISSUES 

72.  A  complete  animal  (or  plant)  is  called  an  organism. 
The  cells  .  constituting   it  and   working    harmoniously  to- 
gether  were   likened   to   a   human   community  or   town. 
Such  a  comparison  helps  us  to  realize  how  complex  and 
mysterious  is  an  animal  body,  and  how  wonderful  are  the 
processes  of  life.     But  the  relation  between  the  cells   is 
much  closer  than  that  between  the  individuals  of  a  com- 
munity.    A  marked  difference  is  that  the  human  being  can 
move  as  a  whole,  can  change  place  in  space,  can  act  with 
all  the  organs  in  the  organism  working  in  unison.     The 
energy  stored  in  the  body  enables  it  to  do  these  things, 
and  the  two  tissues  that  chiefly  expend  the  energy  and 
give  us  the  ability  to  do  things,  to  act,  are  the  nerve  tissue 
and  the  muscular  tissue.     How  is  energy,  or  the  ability  to 
do  work,  stored  in  the  body  ? 

73.  Oxidation.  —  We  know  that  this  energy  arises  from  a 
kind  of  combustion  or  slow  burning,  thus  resembling  in 
its  source  the  energy  of  the  steam  engine.     That  some- 
thing besides  wood  or  coal  is  necessary  to  a  fire  can  be 
shown  by  shutting  off  entirely  the  draught  of  the  stove. 
Fire  and  all  other  forms  of  combustion  depend  upon  a 
process  called  oxidation.     This  consists  in  the  uniting  of 
oxygen,  the  active  element  of  the  air,  with  carbon,  hydrogen, 
and  other  elements  in  wood,  coal,  etc.     Bread,  meat,  and 
other  foods  contain  these  latter  elements.     That  carbon  is 
in  sugar,  for  instance,  can  be  easily  proved  by  charring 
sugar  upon  the  stove,  the  charcoal  thus  produced  being  a 

44 


THE  MASTER    TISSUES  45 

form  of  carbon.  Compounds  containing  these  elements 
are  taken  into  the  body  through  the  digestive  organs, 
carried  around  by  the  fluid  portion  of  the  blood,  and 
stored  up  in  the  cells  ready  for  union  with  oxygen  by  the 
process  of  slow  combustion,  or  slow  oxidation,  of  which 
the  activity  called  animal  life  seems  to  consist.  The  oxy- 
gen, on  the  other  hand,  enters  the  body  through  the  lungs 
and  is  carried  to  the  tissues  by  the  red  corpuscles  of  the 
blood.  Thus  is  energy  stored  in  the  body,  the  oxygen 
being  ready  to  unite  with  the  other  elements,  giving  rise 
to  heat  and  motion.  The  rate  and  manner  of  this  union 
are  regulated  by  one  of  the  master'  tissues,  the  nerves; 
while  the  application  of  the  energy  so  as  to  produce 
motion  is  the  function  of  the  muscular  tissue. 

74.  The  " burning"  of  food  substances  in  the  muscle  is 
essentially  the  same  process  as  the  burning  of  coal  in  the 
furnace  of   the  engine,  but  in  the  muscle    the   oxidation 
takes  place  under  peculiar  conditions  not  at  present  thor- 
oughly understood,   at  a  temperature  of   less  than    100° 
Fahrenheit,  while  for  ordinary  combustion  a  temperature 
of  several  hundred  degrees  is  required. 

75.  The  body  resembles  a  locomotive  in  having  warmth 
and  motion  as  a  result  of  the  union  of  fuel  and  oxygen ; 
but  it  differs   from  the  locomotive,  since   the   intelligent 
engineer  is  an  organic  part  of  it,  and  since  the  oxidation  in 
the  body  is  in  the  presence  of  moisture,  and  so  gradual 
that  it  is  not  a  true  fire  accompanied  by  light.     Moreover, 
the  body  can  repair  itself  as  it  wears  out,  and  the  engine 
cannot.     The  energy  stored   in   the   body  is   used   more 
economically  and  effectively  than  any  steam  engine  can 
use  fuel.     This  we  might  well  expect  from  the  fact  that 
the  engineer  is  a  part  of  the  engine. 

76.  Muscular  Tissue.  —  How  does  the  oxidation  of  food 
produce  motion  ?     We  learn  that  the  ameba   and   other 
one-celled  animals  can  change  their  shapes.     Many  of  the 


46 


ELEMENTS   OF  PHYSIOLOGY 


cells  in  the  body  have  lost  this  power,  but  the  muscle  cells 
retain  it.  Figure  27  shows  a  muscle  cell  of  one  form. 
Figure  45  shows  muscle  cells  of  another  form.  There  are 
other  forms  of  muscle  cells,  but  they  are  all  alike  in  the 
fact  that  under  certain  conditions  they  get  broader  and 
shorter.  Suppose  we  have  a  row  of  cells  in  a  muscular 
tissue.  Think,  for  instance,  of  the  muscle  in  the  upper 
arm  that  causes  the  elbow  to  bend  when  the  muscle 
becomes  shorter.  It  is  plain  that  the  shortening  of  the 
whole  muscle  will  be  equal  to  the  sum  of  the  shortening 
of  all  the  cells  in  a  line  extending  along 
the  muscle,  and  its  thickening  will  be 
equal  to  the  thickening  of  the  individual 
cells  as  they  lie  side  by  side.  But  what 
makes  the  muscle  cells  change  shape? 
We  have  found  that  the  food  brought 
to  the  muscle  by  the  blood  is  stored  in 
the  muscle  cells  in  a  condition  just  ready 
for  union  with  the  oxygen  which  has  also 
****•  stored  in  the  cells.  This  union,  or 
combustion,  does  not  occur  continually, 
^llt  js  caused  when  a  certain  change 
called  a  nerve  impulse  comes  to  the  mus- 
cle along  a  nerve  fiber;  and  when  the  impulse  comes, 
carbonic  acid  gas,  or  carbon  dioxid,  is  formed  and  the 
muscle  cells  become  broader  and  shorter. 

77.  Nervous  Tissue.  —  Knowing,  as  you  do,  how  micro- 
scopic the  cells  are  in  size,  what  would  you  think  if  you 
were  told  that  there  are  cells  in  the  body  that  have  parts 
which  extend  several  feet  in  length  !  There  are  cells  with 
branches  which  reach,  for  instance,  from  the  backbone  to 
the  toes  (Fig.  193).  A  mass  of  nerve  tissue  called  the 
brain  occupies  almost  all  of  the  skull,  and  forms  the 
spinal  cord,  or  spinal  marrow.  Nerve  tissue  forms  also 
the  glistening  white  cords,  called  nerves,  going  from  the 
brain  and  spinal  cord  to  all  parts  of  the  body  (Fig.  46). 


of  the  Heart. 


THE  MASTER    TISSUES 


47 


FIG.  46.  —  The   General  Arrangement    of    the   Nervous    System    (viewed    from 

behind). 
Showing  the  brain,  the  spinal  cord  and  the  chief  nerves  that  branch  from  it. 


48  ELEMENTS   OF  PHYSIOLOGY 

When  eating  pork,  did  you  ever  see  the  spinal  cord  of  a  hog  ? 
How  large  was  the  cord  ?  Have  you  seen  a  hog's  brain 
or  the  brain  of  an  ox?  However  complicated  nerve  tissue 
may  seem  to  be,  it  is  found  to  consist  of  nerve  cells  and 
their  branches,  called  nerve  fibers  (Fig.  48).  Some  cells 
are  arranged  in  a  distinct  mass  called  a  ganglion. 

78.  A  nerve  consists  of  a  great  number  of  cell-branches 
or  nerve  fibers,  just  as  a  number  of  telephone  wires  are 
sometimes  bound  together  in  a  cable.     Nerve  cells  grow, 
become  active  and  die,  like  other  cells,  and  like  other  cells 
they  consist  of  protoplasm  with  a  nucleus  and  nucleolus. 
A  number  of  processes  branch  off  from  them,  some  cells 
giving  off  only  one  or  two,  others  many  (Fig.  47).     One  of 
these  processes  forms  a  nerve  fiber.     The  axis,  or  central 
part  of  the  fiber,  is  a  continuation  of  the  jellylike  proto- 
plasm of   the  cell ;   this  core  is  the  essential  part  of  the 
fiber.     The  axis  is  surrounded  in  most  fibers  by  a  sheath 
of   fatty  material  (Fig.    48).     This    is    for    nourishment 
and  protection  of  the  axis,  and  it  is  this  which  gives  to  the 
fiber  its  characteristic  ivory-white  appearance.     The  whole 
is  strengthened  by  being  inclosed  in  a  thin,  delicate  sheath 
of  connective  tissue.     Some  of  the  nerves  go  to  the  mus- 
cles, and  passing  between  the  bundles  of  fibers,  soon  divide 
into  branches,  for  we  have  seen  that  the  nerves  are  bun- 
dles of  separate  fibers.     They  subdivide  in  the  muscles  till 
they  ultimately  send  a  single  nerve  fiber  to  each  individual 
muscle  fiber. 

79.  How  Nerves  and  Muscles  work  together.  —  Suppose 
you   put   your  hand  on  a  hot  stovepipe  or  poker;    it  is 
immediately  jerked  away.     How  does  this  wonderful  thing 
happen  ?     It  is  found  that  the  heat  of  the  iron  causes  a 
disturbance  in  a  nerve  fiber  ending  just  under  the  skin  of 
the  finger.    This  disturbance  travels  rapidly  along  the  axis, 
or  core,  of  the  nerve,  and  is  called  an  impulse.     It  is  not 
a  visible  change,  but  some  influence  that  travels  from  par- 


THE  MASTER    TISSUES 


49 


ticle  to  particle.  It  resembles  electricity  somewhat,  but 
some  physiologists  think  it  is  like  a  wave  of  chemical 
change,  running  along  the  nerve  faster  than  a  railway 
train  can  run.  It  reaches  a  nerve  cell  in  the  spinal  cord. 
The  disturbance^  there  causes  the  cell  to  send  out  impulses 
along  its  other  branches  or 
fibers.  Some  impulses  are 
sent  down  the  arm  again  to 
its  muscles,  causing  them 
to  contract,  and  the  arm  is 
jerked  away,  as  we  say,  by 
reflex  action,  or  action  with- 
out will  on  our  part.  Other 
impulses  go  at  the  same  time 
to  the  brain,  and  we  become 
conscious  of  what  has  hap- 
pened. The  nerves  which 
carry  impulses  to  the  nerve 
cells  are  called  sensory 
nerves,  or  nerves  of  feeling,  and  those  which  carry 
impulses  from  the  cells  to  the  muscles  are  called  motor 
nerves,  or  nerves  of  motion.  Nerves  transmit  impulses, 
but  do  not  originate  them.  An  impulse  in  a  nerve  can  be 
excited  by  pinching,  pricking,  electricity,  a  drop  of  acid, 


FIG.  47.  —A  Nerve  Cell. 

From  the  gray  matter  of  the  spinal  cord, 
magnified. 


FIG.  48.  —  Nerve  Fiber,  highly  magnified. 
Showing  axis  (gray),  sheath  of  fatty  material  (black),  sheath  of  connective  tissue  (white). 

a  hot  wire,  a  cold  object,  or  a  thought.  Reflex  action 
always  occurs  on  account  of  some  influence  from  the  outer 
world,  but  voluntary  action  comes  from  activity  in  the  brain. 
80.  Suppose  you  step  out  of  a  warm  house  into  a  cold 
wind.  The  face  immediately  blanches  or  turns  white. 
Let  us  see  how  this  is  accounted  for.  There  are  muscle 
fibers  in  the  walls  of  the  blood  vessels.  The  cold  air 


50  ELEMENTS   OF  PHYSIOLOGY 

excites  impulses  in  the  sensory  nerves  of  the  face,  which 
travel  to  the  enlargement  at  the  top  of  the  spinal  cord 
just  at  the  base  of  the  brain,  called  the  spinal  bidb,  or 
medulla  oblongata  (Plate  VI).  Here  it  reaches  a  nerve 
center  which  reflects  impulses  along  the  nerves  that  go 
to  the  muscle  fibers  in  the  walls  of  the  blood  vessels, 
causing  them  to  contract,  and  the  face  turns  white.  Thus 
we  see  how  closely  related  are  the  two  master  tissues. 

81.  If  we  consider  that  the  nerves  reach  almost  every- 
where in  the  body,  and  that  the  muscles  of  the  body  weigh 
nearly  as  much  as  all  other  tissues  together,  we  realize  how 
important  the  master  tissues  are.  Let  us  count  up  some  of 
the  activities  in  which  the  muscles  are  necessary  :  swallow- 
ing, digesting  food,  breathing,  blushing,  writing,  walking, 
talking,  looking,  tasting,  chewing,  frowning,  smiling,  laugh- 
ing, circulation  of  the  blood.  There  are  only  a  few  things, 
such  as  hearing,  smelling,  and  feeling,  that  can  sometimes 
be  accomplished  without  muscles.  It  is  now  taught  by 
those  who  study  psychology,  or  the  science  of  the  mind, 
that  emotions  of  the  mind  are  always  simultaneous  with  a 
change  in  the  circulation  of  the  blood,  and  that  emotion 
cannot  be  felt  without  a  change  in  the  heart  or  other  blood 
vessels. 


CHAPTER   V 
SUBSTANCES  FORMING  THE  BODY;   OXIDATION 

82.  Oxidation. — You  learned  that  oxidation  is  the  process 
of  forming  a  union  of  oxygen  with  some  other  substance. 
When  iron  oxidizes,  iron-rust  is  formed.     When  wood  de- 
cays, the  carbon  in  it  oxidizes  and  carbonic  acid  gas  is 
formed.     When  wood  burns,  the  oxidation  is  more  rapid. 
When   hydrogen   is   oxidized,   water   is  formed.     For  in- 
stance, kerosene  oil  contains  hydrogen,  and,  by  burning  it 
in  a  lamp,  water  is  formed  which  collects  on  the  chimney 
when  the  lamp  is  first  lighted,  before  the  glass  has  become 
hot.     You  learned  that  animal  life  seems  to  be  based  upon 
a  process  of  slow  oxidation  taking  place  in  the  tissues  of 
the  body.     Oxygen  has  great  affinity  for  many  substances, 
and  its  union  with,  them  is  accompanied  by  the  production 
of  heat;  thus  the  heat  of  the  body  is  kept  up. 

83.  Plant  and  Animal  Life.  —  In  plant  life  there  is  more 
of  deoxidation  than  of  oxidation.     Carbon  when  alone  is  a 
solid  like  coal,  charcoal,  or  plumbago ;  oxygen  when  alone 
is  a  gas.     When  joined  together  they  make  a  gas  called 
carbonic  acid  gas,  or  carbon  dioxid.     The  leaves  of  a  plant 
absorb  the  carbon  dioxid,  and  by  the  aid  of  the  sunlight 
the  green  coloring  matter  of  the  leaf  separates  the  carbon 
from  the  oxygen.     The  carbon  remains  as  a  part  of  the 
plant,  while  the  oxygen  escapes  from  the  leaves  as  a  gas, 
and  is  ready  to  burn  the  carbon  in  wood  or  sugar  or  ani- 
mal tissue,  and  form  carbon  dioxid  again.     Just  as  much 
heat,  or  energy,  will  be  given  back  in  the  oxidation  as  was 
furnished  by  the  sun  to  the  plant  to  enable  it,  in  the  leaf, 

5' 


52  ELEMENTS   OF  PHYSIOLOGY 

to  separate  the  carbon  from  the  oxygen.  Thus  we  see  how 
animals  and  plants  help  each  other,  and  how  all  nature 
forms  one  harmonious  whole  (Fig.  24). 

84.  List  of  Substances.  —  The  most  important  solid  and 
liquid  substances  of  which  the  body  is  composed  are  water, 
albumin,  fat,  sugar,  salt,  lime,  soda,  potash.     Water,  salt, 
and  lime  'do  not  oxidize,  either  in  or  out   of   the   body. 
Their  use  in  the  body  is  more  mechanical  than  chemical. 

One  ounce  of  albumin  is  completely  oxidized  by  one  and  one  half 

ounces  of  oxygen. 

One  ounce  of  fat  is  completely  oxidized  by  three  ounces  of  oxygen. 
One  ounce  of  sugar  is  completely  oxidized  by  one  and  one  fifth  ounces 

of  oxygen. 

85.  Water.  —  Water  does  not  oxidize.     It  is  composed  of 
two  gases  firmly  united :  hydrogen  and  oxygen ;  that  is, 
water  is  hydrogen  already  oxidized.     Water  forms  three 
fourths  of  the  body.     When  a  solid  substance  is  dissolved 
in  a  liquid  so  that  each  remains  unchanged  in  its  essential 
properties,  the  result  is  a  solution  of  the  solid  in  the  liquid. 
Sugar  in  water  is  sugar  still ;  in  fact  we  can  taste  sugar 
only  when  it  is  dissolved.     Most  solutions  can   go  any- 
where that  water  alone  can  go.     In  the  stomach  the  food 
is  dissolved  and  taken  into  the  circulation.     The  blood 
containing   the   food  in  solution  penetrates  to  the  cells, 
carrying  nourishment  and  washing  away  the  waste  mate- 
rial.    By  means  of  the  perspiration,  water  takes  heat  from 
the  body.     About  three  quarts  of  water  are  taken  into  the 
body  each  day,  either  alone  or  in  watery  foods. 

86.  Albumin  (Proteid).  —  We  learned  that  protoplasm,  or 
living  matter,  differs  from  inorganic  matter  in  containing  an 
albuminous  material,  composed  partly  of  nitrogen.     The 
other  two  oxidizable  foods,  fat  and  sugar,  do  not  contain 
nitrogen.     Pure  nitrogen  is  found  in  the  air,  but  the  body 
cannot  use  it  in  that  form,  for  nitrogen  is  very  inactive  when 
pure ;  when  compounded  in  albumin,  however,  it  gives  to 


SUBSTANCES  FORMING    THE  BODY;    OXIDATION         53 

the  tissues  firmness  and  strength  such  as  sugar  and  fats 
containing  no  nitrogen  cannot  give.  Albumin  is  a  very 
complex  substance  which  only  plants  can  form.  Animals 
must  get  it  from  vegetables,  for  it  is  the  essential  part  of  all 
living  cells.  It  is  similar  to  the  white  or  albumen  of  an  egg. 
Because  it  turns  white  when  heated,  it  is  called  albumen 
(Latin  albus,  white).  Pure  albumin  is  hard  and  brittle,  as 
the  white  of  an  egg  is  when  dried.  The  albumin  of  the  body 
is  a  solution  in  from  five  to  twenty-five  times  its  own 
weight  of  water.  In  the  blood  it  is  liquid,  in  the  flesh 
it  is  jellylike,  in  the  connective  tissue  of  the  skin  it  is  tough 
and  strong.  Albumin  may  be  hardened  or  coagulated  by 
heat ;  the  albumen  of  a  boiled  egg  is  an  example.  Coagu- 
lation of  its  albumin  destroys  the  life  of  a  cell.  Lean  meat, 
cheese,  animal  gelatine,  glue,  and  gluten  are  forms  of  albu- 
min. About  four  and  one  half  ounces  of  pure  albumin 
per  day  are  necessary  to  supply  the  body  in  winter. 

87.  Fats.  —  Fats  are  smooth,  greasy  substances  that  be- 
come liquid  when  heated ;  those  that  are  liquid  at  ordinary 
temperature  are  called  oils.     Fat  is  always  oil  in  the  living 
body  and  is  stored  in  thin-walled  cells  in  connective  tissue 
(Fig.  38).     Fat  is  a  simple  substance  compared  to  albu- 
min ;  divided  in  tiny  particles  or  globules,  and  floating  in 
water,  it  forms  an  emulsion.      Milk  is  an  emulsion.     No 
emulsions  are  permanent ;  e.g.  the  cream  rises  in  the  milk  in 
a  few  hours.     Fat  is  a  living  garment  to  the  body  lying 
underneath  the  skin  to  retain  heat,  protect  from  the  cold, 
and  round  out  the  form.    It  is  a  cushion  for  protection  and 
a  store  of  heat-producing  food  to  be  used  in  sickness  or  at 
any  time  when  food  cannot  be  eaten.     About  three  ounces 
of  fat  should  be  eaten  each  day  in  winter. 

88.  Starch    and    Sugar    (Carbohydrates).  —  Starch    is 
abundant  in    young    plants.      As   the    plant    grows   the 
starch  is  changed  to  wood.     Fruit  while  green  is  chiefly 
starch ;  but  as  it  ripens,  the  starch  is  changed  to  sugar. 


54  ELEMENTS   OF  PHYSIOLOGY 

Starch  and  the  cellulose  of  wood  are  different  forms  of  the 
same  chemical  substance.  Wood  cannot  be  used  in  the  body, 
and  starch  must  be  changed  to  sugar  before  it  can  become 
a  part  of  the  body.  Very  little  sugar  is  found  in  the  body 
at  one  time,  as  it  is  constantly  used  to  produce  warmth. 
About  five  ounces  of  sugar  or  starch  should  be  eaten  each 
day  in  winter,  and  less  in  summer  and  in  warm  climates. 

89.  Other  Substances.  —  There  are  about  six  ounces  of 
salt  in  the  human  body.     We  do  not  give  salt  to  a  pet  cat 
because  it  gets  salt  in  the  flesh  it  eats ;   but  we  give  salt 
to  the  cattle  because  there  is  not  enough  in  vegetable  food 
to  supply  their  needs.     Salt  gives  an  agreeable  taste  to 
food  and  helps  to  keep  the  albumin  of  the  body  dissolved ; 
when  salt  is  not  used,  weakness  results. 

90.  There  are  about  ten  pounds  of  lime  in  the  human 
body.     The  lime  is  deposited  around  the  cells  of  the  bones 
to  give  stiffness  to  the  bones. 

91.  Soda  and  potash  are  called  alkalies.     A  substance 
which  corrodes  metals,  is  sour  to  the  taste  and  unites  with 
soda  or  potash,  is   called   an   acid.     Vinegar   is   an   acid 
substance;  when  soda  is  added  to  it,  both  are  changed,  and 
the  liquid  resulting  has  a  flat,  bitter  taste.     Thus  acids  and 
alkalies  neutralize  each  other.    Saliva  is  formed  in  the  mouth 
and  is  alkaline.     The  gastric  juice  of  the  stomach  is  acid. 
The  blood  is  alkaline  and  performs  the  function  of  destroy- 
ing irritating  acids  in  the  body  by  neutralizing  them. 

92.  The  human  body  is  built  up  of  13  of  the  70  or  more 
elements.     The  13  elements  are  compounded  into  substances 
which  make  up  the  body  of  a  man  weighing  1 50  pounds, 
in  the  following  proportions  :  — 

92  pounds  of  water.  I  pound  of  carbonate  of  lime. 

21  pounds  of  fat.  6  ounces  of  phosphate  of  magnesium. 

1 8  pounds  of  dry  proteid.  2-3  ounces  of  common  salt  and  chlorid 

9  pounds  of  gelatin.  of  potassium. 

8|  pounds  of  phosphate  of  lime.  3  ounces  of  sugar  and  animal  starch. 

As  much  iron  as  there  is  in  four  carpet  tacks. 


SUBSTANCES  FORMING    THE  BODY;    OXIDATION       55 

93.  THOUGHT  LESSON.1  The  Tissues. —  i.  Which  tissue 
has  the  largest  amount  of  intercellular  material  ? 

2.  Which  tissue  has  no  fibers  and  very  little  intercellu- 
lar material,  but  is  composed  almost  wholly  of  cells  ? 

3.  The  walls  of  the  arteries  contain  more  of  the  yellow 
fibers  of  connective  tissue  than  the  veins.     Which   have 
more  elastic  walls? 

4.  Which  tissues  have  cells  without  branches?     Which 
tissues  have  cells  with  branches  ?     Which  tissue  has  two 
kinds  of  cell-branches  or  fibers  ? 

5.  Does  fat  accumulate  in  the  body  within  the  cells  or 
outside  of  them  (Fig.  38)? 

6.  Which  cell  has  the  greatest  variety  of  functions  ? 
Which    cells  are  the  seat  of  great  activity  and  change  ? 
Which  are  moderately  active  ?     Which  are  very  inactive  ? 

7.  Which  tissue  gives  the  least  evidence  under  the  mi- 
croscope of  having  been  formed  by  cells  ? 

8.  Do  adjoining  cells  have  a  common  wall  separating 
them,  or  does  each  cell  have  its  own  wall?     Are  instan- 
ces of  both  kinds  of  cells  to  be  found  ? 

9.  Choose  a  cell  and  write  its  "  biography." 

10.  How  does  a  tissue  grow?     Does  a  scar  on  a  child, 
or  a  "  brand  "  on  a  calf  or  other  young  animal,  enlarge  as 
its  body  grows  ? 

11.  State  the  difference  between  albumen  and  albumin. 

1  The  teacher  may  require  the  answers  to  the  questions  in  this  Thought 
Lesson  to  be  prepared  in  writing.  In  class  the  pupils  should  change  (but  not 
exchange)  papers,  and  criticise  and  correct  the  answers  as  they  are  read  aloud 
from  different  papers.  The  same  plan  is  applicable  to  the  other  Thought 
Lessons. 


PART   II.     HOW   THE   BODY   IS   MOVED 
CHAPTER  VI 

THE   SKELETON 

94.  Animals  and  their  Skeletons.  —  There  are  some  ani- 
mals, such  as  the  slug  (a  kind  of  snail  without  a  shell, 
Fig.  50)  and  the  jellyfish,  that  do  not  possess  any  hard  part 
corresponding  to  a  skeleton.     Such  an  animal,  if  it  lives 
on  land,  lies  flat  on  the  ground  and  moves  slowly  and  with 
difficulty.     Some  animals,  as  the  crawfish  and  the  beetle, 
have  the  skeleton  on  the  outside  in  the  form  of  a  crust. 

95.  Three  Functions  of  the  Skeleton  and  the  Three  Shapes 
of  Bones.  —  Even  in  man,  so  capable  of  self-protection,  it 
is  necessary  to  have  the  skeleton,  or  hard  part,  to  protect 
some  of  the  most  delicate   organs.     The  bones   for   this 
purpose  are  flat,  as  the  breastbone   and   shoulder   blade, 
the  ribs,  which  protect  the  heart  and  lungs,  and  the  skull 
bones,  which  protect  the  soft  and   delicate    brain.      The 
muscles  by  their  shortening  accomplish  very  simple  and 
imperfect  motions ;  by  using  the  bones  for  support  and  as 
levers,  this  motion  is  changed  in  rate,  direction,  and  place 
of  application. 

The  long  bones  of  the  arms  and  legs,  with  the  fingers 
and  toes,  have  motion  as  their  chief  function.  The  ribs  are 
flat  but  are  the  longest  bones  in  the  body  in  proportion 
to  their  size,  and  enable  us  to  perform  the  important 
motions  of  breathing.  Yet  they  are  classed  as  flat  bones, 
for  they  lack  the  round  shaft  and  enlarged  ends  or  heads, 
which  typical  long  bones  have.  Even  the  bones  of  the 

56 


THE  SKELETON 


57 


NASAL  BONES-" 


(SCAPULA)  -~ 


.1  %THE  CRANfUM. 

'-MALAR  (CH  EEI< 
—  SUPERIOR  MAXILLARY  BONES 
-INFERIOR  MAXILLARY  BONE 

SPWAL  COLUMN  CERVICAL  REGION, 
^-(CLAVICLE)  COLLAR  BONE 


-HUMERUS 


FIG.  49.  — The  Skeleton. 


ELEMENTS   OF  PHYSIOLOGY 


FIG.  50.  — The  Slug. 


instep,  palm,  fingers,  and  toes,  which  are  the  smallest  of 
the  long  bones,  have  the  shaft  and 
heads. 

The  many  small  short  bones  are 
stronger  than  the  long  slender 
bones,  or  the  flat  thin  ones.  These 
bones  are  called  irregular  bones. 
They  are  not  easily  broken  and 
their  chief  function  is  support. 

They  are  found  in  the  spine,  the  ankle,  the  wrist,  the  knee, 

and  the  face.     We  should  remember   that  the  irregular 

bones  also  as- 
sist in  the  two 

other  functions 

of     protection 

and    motion; 

also  that  the 

long  bones  and 

the  flat  bones 

are  not   con- 
fined to  one 

function  but 

participate     in 

all  three  func- 
tions (Fig.  49). 
96.    Another 

Use  of  Bories.  — 

Recent  discov- 

erie  s     have 

shown  that  the 

red  marrow  in 

the  small  cavi- 


FlG.  51.  —  Side  View  of  Skull. 

larger  bones  are  named  in  the  figure.  The  lower  jaw  is  dropped 
down.  Its  socket  in  the  skull  is  shown  in  front  of  the  opening  of 
the  ear,  au ;  z,  process  of  temporal  passing  to  malar,  or  cheek  bone ; 
c,  one  of  the  condyles  or  projections  which  rest  in  sockets  on  the  high- 
est vertebra;  tk,  hyoid  bone,  not  joined  to  any  other  bone,  except  by 
muscles;  au,  opening  of  ear  ;  /,  lachrymal  bone.  A  small  part  of 
sphenoid  bone  is  shown  ;  the  main  part  is  at  base  of  skull. 

The  eight  cranial  bones  are  :  — 
. .  r  One  Frontal  (forehead).  One  Occipital  (back  and  floor). 

Spongy   TwQ  Parietal  (sides  and  roof).  One  Sphenoid  (central  floor). 

boneS    1S  active   Two  TemP°ral  (sides).  One  Ethmoid  (front  floor). 

in  producing  the  red  corpuscles  found  in  the  blood. 


THE  SKELETON  59 

97.  Number  of  Bones.  —  There   are   206   bones   in   the 
adult  human  body.     The  number  of  bones  is  greatest  in 
childhood  and   diminishes   in    old  age  by  the  obliteration 
of  joints.     The  head  has  22  bones  in  adult  life,  more  in 
infancy,  and  fewer  in  old  age. 

98.  General  Arrangement  of  the  Skeleton  (Fig.  49).  — 
The   central  part  of  the  skeleton,  called  the  vertebral  or 
spinal  column,  forms  a  firm,  but  flexible  axis.     The  head 
rests  upon  the  top  of  this  column.    The  ribs  are  attached 
at  its  sides  to  make  the  walls  of  the  chest.     The  shoul- 
der  girdle  rests    upon    the    chest,  and   the   hip  girdle  is 
attached  to  the  base  of  the  spinal  column.     These  girdles 
connect    the     upper    and    lower    limbs    with    the    trunk. 
The  bones  of  the  head  and  trunk  form  the  axial  skeleton. 
The  bones  of  the  girdles    and   limbs  are   called  the  ap- 
pended skeleton,   since   they   are  appended   to    the   axial 
skeleton. 

99.  The   Skull  (Figs.    51    and    52)  is  the    cranium,  or 
casket   which   contains   the  brain,  and    the  facial  bones. 
The  arched  form  of  the  skull  is  the  best  shape  for  resisting 
blows  and  pressure.     Its  bones  are  so  firm  and  hard  that 
bullets   sometimes    glance   from   it.      The   occipital   bone 
curves  under  at  the  back  of  the  neck  to  aid  in  forming 
the  floor  of  the  skull.    It  has  two  projections  called  condyles 
("knuckles")  situated  just  behind  its  junction  with  the  sphe- 
noid ("  wedgelike")  bone.    The  condyles  fit  into  depressions 
(Fig-  53)  m  the  uppermost  vertebra ;  thus  the  head  rests  and 
rocks  upon  the  spinal  column.     Grasp  the  neck  with  both 
hands    so   as  to   hold    it    motionless    and    stiff,   and   find 
whether  the  head  rocks  forward  and  backward,  or  side- 
wise.     Between  the  condyles  is  a  large  opening  through 
which  the  spinal  cord  goes  from  the  brain. 

Of  the  eight  cranial  bones,  how  many  are  in  pairs,  and 
how  many  are  not  ?  Those  in  pairs  are  located  at  the 
sides  of  the  cranium.  The  hair  over  the  temples  first 


6o 


ELEMENTS   OF  PHYSIOLOGY 


turns  white,  thus  reminding  us  of  the  temporary  nature 
of  life.  What  bones  receive  their  name  because  of 
this  ? 

100.  The  Bones   of  the   Face  are  fourteen  in  number, 
twelve  being  in  symmetrical  pairs,  and  two  unpaired :  the 
two  malar  bones  forming  the  prominences  of  the  cheeks  ; 

two  nasal 
bones,  small 
and  slender, 
forming  the 
bridge  of  the 
nose ;  two  up- 
per maxillary 
bones,  form- 
ing the  upper 
jaw;  one  in- 
ferior maxil- 
lary, the  lower 
jaw  ;  one  vo- 
mer,  the  bony 
partition  be- 
tween the 
nostrils ;  two 
lachrymal 

bones  in  the  eye  sockets  ;  two  palate  bones  in  the  roof  of 
the  mouth  ;  two  turbinated  bones  in  the  interior  of  the 
nose  (Plate  VII).  Is  any  bone  of  the  head  movable  upon 
the  others  ? 

101.  The  Hyoid  Bone,  called   also  the  tongue  bone,  is 
U-shaped  (this  is  the  meaning  of  its  name  in  Greek)  and 
lies  in  the  front  of  the  neck,  where  it  may  be  felt  above  the 
Adam's   apple.     Can  you  move  it  from  side  to  side  with 
your  hand  (Figs.    51   and   129)?     Does   it   feel  rough   or 
smooth  ?     It  forms  points  of  attachment  for  numerous  mus- 
cles, the  muscular  tongue  being  attached  to  it  above, 


FlG.  52.  —  Bones  of  the  Head. 

i,  Frontal  bone;  2,  parietal  bone;  3,  temporal  bone;  4,  occipital 
bone;  5,  nasal  bone  ;  6,  malar  bone;  7,  upper  jaw;  8,  lachrymal 
bone  ;  9,  lower  jaw  (maxilla). 


THE  SKELETON 


61 


102.  The  Vertebral  Column.  — The 

spinal  column  consists  in  the  adult  of 
twenty-six  bones  (Fig.  53).  Twenty- 
four  of  these  bones  have  a  similar 
shape,  and  each  is  called  a  vertebra 
(Latin,  "that  which  turns  ").  The 
other  two  have  the  names  of  sacrum 
and  coccyx.  The  first  seven  verte- 
brae are  in  the  neck  and  are  called 
cervical  ("of  the  neck  ").  The  next 
twelve  are  those  to  which  the  ribs 
are  attached  and  are  called  thoracic 
or  dorsal  ("of  the  back")  (see  Fig. 
49).  The  next  five  vertebras  are  in 
the  loins  or  lumbar  region  and  are 
called  lumbar ("  of  the  loins  ").  They 
are  the  largest  of  the  vertebrae.  The 
lowest  lumbar  vertebra  rests  upon 
the  sacrum  ("sacred,"  because  this 
bone  of  lower  animals  was  once  used 
in  sacrifice).  In  infancy  the  sacrum 
consists  of  five  vertebrae ;  these  begin 
uniting  at  two  years  of  age  and  com- 
plete the  union  at  twenty  years.  The 
coccyx  ("cuckoo,"  from  resemblance 
to  bill  of  cuckoo),  or  last  bone  of  the 
column,  is  that  part  of  the  skeleton 
which  in  the  lower  animals  forms  the 
tail.  In  infancy  it  consists  of  four 
small  bones  which  later  unite  into  one. 
The  coccyx  is  of  little  use,  but  the  sa- 


tTr 


FIG.    53.  —  Spinal    Column 
(seen  from  behind). 


crum  is  a  highly  important  bone,  since  '^te^ST  «*"£ 

to  its  sides  are  attached  the  bones  of  7  cervical,  12  thoracic,  5  ium- 

-                    .                                 «   •    i  bar,  vertebrae.    Do  the  sacrum 

the  pelviC  arch,  by  Which  the  Weight  Of  and  coccyx  show  evidence  of 

the  body  is  transmitted  to  the  legs.  J™nt|  J""  divided  in  early 


ELEMENTS   OF  PHYSIOLOGY 


.8 


103.  A  Single  Vertebra  consists  of  a  thick  disk  called  the 
body  of  the  vertebra  (Fig.   54);    behind  the   disk   is  an 
arch,  and  upon  the  arch  are  i 

several  projections  called  pro- 
cesses.    The  projection  at  the 
rear  is  called  the  spinous  pro- 
cess, those   at  the  sides  are 
called    transverse    processes. 
All  three  serve  for  the  attach- 
ment of  muscles  which  prevent 
the  body  from  bending 
forward  under  its  own 
weight.      The  holes 
under  the  arches  of  the 
vertebrae  form  a  passage  for 
the  spinal  cord. 

.  FIG.  54.  — Thoracic  Vertebra 

104.  The    first    cervical  (top  view). 

Vertebra,  Or  atlas  (Fig.  55),  has      i,  body  ;  2,  hole  which  forms  part  of  verte- 

,        ,  .       ,  j  bral  canal  ;   3,  spinous  process;   4,  trans- 

nO  body  J    it     has     tWO    depreS-          verse  process ;  5)  surface  which  articulates 

sions  into  which  the  occipital  ££  ^^£^  ^  <• sur' 
condyles  fit.  The  head  rocks 

back  and  forth  (nods)  by  the  condyles  slipping  in  the  two 
depressions,  or  sockets,  of  the  atlas.  The  second  vertebra 
(Fig.  56)  is  called  the  axis.  It  has  a  peg  in  place  of  a  body  ; 
this  peg  projects  into  the  hole  in  the  atlas,  making  a  pivot 

joint  upon  which  the  atlas  and 
head  turn  (Fig.  57).  When  the 
head  moves  around,  the  atlas 
'moves  with  it,  rotating  upon  the 
peg  of  the  axis.  Can  you  find 
A  ^w  out  why  the  atlas  received  its 

FIG.  55.  —  The  Atlas  (from  above),  name  ? 

105.  Between  the  vertebrae  are 
elastic     cushions    of     cartilage, 
which  give  flexibility  to  the  spinal  column  and  prevent  injuri- 


a,  sockets  for  articulation  with  skull  ; 
b,  peg  of  axis.with  ligament  behind  it. 


THE  SKELETON 


FIG.  56.  —  The  Axis 
(side  view). 

a,  one  of  the  areas  for 
articulation  with  atlas  ; 
6,  pivot  or  peg. 


.       b 

FIG.  57. 
a,  atlas  ;  b,  axis  ;  c,  pivot  of  the  axis. 


a •- 


ous  jarring  of  the  brain  and  spinal  cord.  Otherwise,  the  head 
would  receive  a  great  shock  whenever  one  alighted  upon  the 
feet  in  jumping  from  a  height.  The  spinal  column  is 

so     constructed 

as   to    furnish 

strength  to  sup- 
port   the    body, 

to  facilitate  the 

attachment      of 

the  organs  to  it, 

to  furnish  a  safe 

passage  for  the 

spinal     cord, — 

yet  while  accomplishing  these  several 
purposes,  to  allow  the  body  to  bend  without  displacing 
any  of  the  numerous  organs 
of  the  trunk. 

106.  The  Thorax,  or  chest, 
is  formed  in  the  rear  by  the 
twelve  thoracic  vertebrae ;  in 
front,  somewhat  parallel  to 
the  spinal  column,  but  ap- 
proaching it  above,  is  the 
sternum,  or  breastbone  (Fig. 
58).  Twelve  ribs  curve 
around  each  side.  Each  rib 
joins  one  of  the  thoracic 
vertebrae  behind.  The  first 
seven  pairs  directly  join  the 
sternum  in  front  by  means 
of  short  cartilages,  and  are 
called  true  ribs.  The  next 
three  pairs,  called  false  ribs, 
do  not  reach  the  sternum, 
but  each  rib  unites  to  the  rib 


-10 


I  -" 


FIG.  58.  —  Bony  Walls  of  Thorax. 

a,  b,  vertebral  column;  c,  sternum;  d,  costal 
cartilages;  e,  united  cartilages  of  8th,  gth, 
and  loth  ribs;  n,  12,  floating  ribs. 


64 


ELEMENTS   OF  PHYSIOLOGY 


above  by  a  long  cartilage.  The  last  two  pairs  are  called 
floating  ribs,  since  the  front  ends  are  not  attached  to  a  bone 
either  directly,  like  the  true  ribs,  or  indirectly,  like  the  false 
ribs,  but  rest  in  the  muscular  walls  of  the  waist.  (Describe 
the  microscopic  structure  of  cartilage  as  shown  in  Fig.  43.) 

107.  The  Appended  Skeleton.  —  This  part  of  the  skeleton 
consists  of  the  four  limbs  and  the  bones  which  serve  to 
attach  them  to  the  trunk  or  axial  skeleton. 

108.  Shoulder  Girdle.  —  The   arms  are  attached   to  the 
trunk  by  the  shoulder  girdle.     This  consists  (Fig.  49)  of 

four  bones,  two  on  each  side, 
the  scapulae,  or  shoulder 
blades,  and  the  clavicles,  or 
collar  bones.  Each  shoulder 
is  composed  of  a  clavicle 
( "  key,"  from  its  resem- 
blance to  the  ancient  form 
of  that  article)  and  a  scap- 
ula (Fig.  59).  The  scapula 
(a  "trowel")  occupies  the 
rear  part  of  the  shoulder. 
It  is  a  large  flat  bone,  of 
triangular  shape,  and  bears 
in  the  end  at  the  angle 
of  the  shoulder  a  shallow 
socket  into  which  is  fitted  the  end  of  the  upper  bone  of  the 
arm.  The  clavicle  is  a  slender  bone,  round  and  slightly 
curved,  which  occupies  the  front  of  the  shoulder,  and  is 
joined  at  one  end  to  the  scapula  and  at  the  other  to  the 
sternum.  The  clavicles  can  be  felt  at  the  right  and  left 
of  the  base  of  the  neck. 

109.  The  Arm  consists  of  the  upper  arm,  forearm,  wrist, 
and  hand  (Fig.  60).     The  upper  arm  extends  to  the  elbow 
and  has  only  one  bone,  the  humerus.     From  the  elbow  to 
the  wrist  is  the  forearm,  formed  of  two  bones,  arranged 


FlG.  59.  —  Clavicle,  Scapula,  and  Head 
of  Humerus. 

Disjointed  and  seen  from  behind. 


THE  SKELETON 


parallel  to  each  other;  the  ulna  is  on  the  outside,  the  side 
corresponding  to  the    little  finger;  the 


.17171 


scap 


phi 


radius  occupies  the 
inner  side,  the  same 
side  as  the  thumb.  At 
the  lower  end  of  each, 
a  bump  may  be  felt, 
the  bump  on  the  ulna 
being  larger.  The 
wrist  is  called  the 
carpus,  and  is  com- 
posed of  eight  small 
bones  arranged  paral- 
lel in  two  rows,  four  in 
each  row,  running 
across  the  wrist.  Next 
follows  \ho,metacarp2is 
("beyond  the carpus") 
(Fig.  60),  or  the  bones 
in  the  palm  of  the 
hand.  The  palm  is 
composed  of  five  long 
bones,  each  serving  to 
support  a  finger  or 
thumb.  Each  finger 
is  composed  of  three 
small  bones  called 
phalanges,  ("rows  of 


Jem — - 


FIG.  60.— The  Arm  and  soldiers");  the  thumb 

has   only  two.      The  FIG.  61.—  Bones  of  the 

Seen  from  the  front.     Why  W          H  T     o- 

do  the    fingers    seem    so  thumb    is     more     mOV- 
long?  TII  i         r  Front  view. 

able  than  the  fingers, 

and  can  be  opposed  to  each  of  them.  The  arm  therefore 
consists  of  thirty  bones;  the  upper  arm  has  one  ;  forearm, 
two;  wrist,  eight;  palm,  five;  fingers,  fourteen. 


66  ELEMENTS   OF  PHYSIOLOGY 

110.  The  Leg.  —  The  skeleton  of  a  lower  limb  has  a  strik- 
ing resemblance  to  that  of  an  upper  limb  (Fig.  61).  The 
hip  girdle,  corresponding  to  the  shoulder  girdle,  forms 
the  hip.  The  hip  bones,  or  innominate  ("nameless," 
because  they  do  not  resemble  anything)  bones,  are 
large,  flat,  and  somewhat  semicircular  in  shape.  They 
meet  in  front  (Fig.  62),  but  behind  they  join  the  portion 
of  the  spinal  column  called  the  sacrum,  which  separates 


FIG.  62.  — The  Pelvis. 

Sac,  Sacrum  ,  cocc,  coccyx  ;  acet  (acetabulum) ,  cup  for  head  of  femur  ;  5LV,  fifth  lumbar 

vertebra. 

them  and  forms,  as  it  were,  the  keystone  of  the  arch  (Fig. 
62).  Thus  is  formed  a  large  band  of  bone  inclosing  a 
basin-shaped  space,  called  the  pelvis  ("  basin  "),  which  con- 
tains the  bladder  and  other  organs.  There  is  a  deep  socket 
at  the  side  in  each  innominate  bone.  This  socket  is  occu- 
pied by  the  round  head  found  on  the  upper  end  of  the 
thigh  bone,  or  femur.  The  femur  is  the  largest  and  long- 
est bone  in  the  body  (Figs.  63,  64). 

111.    The  leg  below  the  knee,  like  the  forearm,  is  com- 
posed of  two  parallel  bones.     They  are  not  equal  in  size, 


THE   SKELETON 


67 


like  the  radius  and  ulna,  however,  one,  called  the  tibia,  be- 
ing much  larger  than  the  other,  the  fibula  (Fig.  61).     The 
E  latter  bone  is  merely  a  brace  to  the  large 

tibia,    which    forms   the 

joints    with    the    femur 

above  and  the  foot  below. 

There    is   a    bony  disk 
—  D     embedded  in  the   great 

tendon   over   the    knee, 

forming  a  protection  to 

the  knee  joint;    this  is 

called  the  patella,  or  knee- 
pan.    In  which  direction 
"" c       can  you   move   the    pa- 
tella to  and  fro  with  the 

hand,   when    the  leg  is 

straight    and    the    heel 

resting  upon  the  floor? 
112.    Like   the    hand, 

the     foot     consists     of 

three  parts.    The  tarsus, 

or   ankle,    is  formed  of 

seven    bones,    although 

the    carpus    has    eight. 

The  metatarsus,  like  the 

metacarpus,  is  composed 

FIG.  63.-  Front  View    Qf    fiye    bo  arranged     FIG  64. -Femur  (seen 

of  Femur.  from  behind). 

A        fi,  i,   A  t\,       parallel  to  one  another. 

A,  smooth  head  of  bone  jn  case  of  a  faU}  tne  femur 

for  articulating    with    which   SCrVC  for  the  baSC 

The    tOCS 


hipbone;     C,    shaft; 

D  and  E,  rough  pro-  of    the     tOCS. 

cesses  to  which  mus-  1.1  i 

cies  are  attached ;  F,  have  the  same  number 


would  be  likely  to  break 
at  the  turn  or  angle  near 
the  hip,  if  there  were 
not  a  brace  there  which 
prevents  this. 


•^  of  bones  as  the  fingers, 

and  have  the  same  name,  the  phalanges. 
How  many  phalanges  are  there  in  the  great  toe  ?  The  leg, 
like  the  arm,  contains  thirty  bones.  How  can  this  be  true 


68 


ELEMENTS   OF  PHYSIOLOGY 


since  the  ankle  has  only  seven  bones  as  compared  with 
eight  in  the  wrist  ? 

113.    THOUGHT  LESSON.      Classification  of  the  Bones.— 

Copy  and  fill  out 
the  following  table. 
Place  after  each 
name  in  the  first 
column  the  number 
of  the  bones  of  that 
name.  This  number 
should  be  repeated 
in  the  column  to 
which  the  shape  as- 
signs the  bone.  For 
instance,  there  are 
two  femur  bones, 
"  2 "  is  therefore 
placed  in  the  first 
column ;  they  are 
long,  therefore  "  2  " 
is  placed  also  in 
the  second  column. 
(See  Fig.  49.) 

114.  Joints.— The 
meeting  of  two 
bones  is  called  a 
joint.  Joints  are  of 
two  general  kinds, 
fixed  (or  immovable) 
and  movable.  The 
hip  bones  join  the  sa- 
crum by  fixed  joints. 
The  most  remarka- 
ble fixed  joints  are  those  in  the  skull,  the  bones  of  which 
fit  into  one  another  by  means  of  toothed  edges,  forming 


NAMES 

No.  OF  BONES 

05 

*J 

£i 

$ 

No.  OF 
FLAT  BONES 

NO.  OF-lRREG- 

ULAR  BONES 

Face     .     .     . 

Cranium    . 

Vertebra  .     . 

Sacrum 

Coccyx 

Innominate    . 

Rib.     ... 

Sternum    . 

Clavicle     . 

Scapula 

Humerus  . 

Ulna     .     .     . 

Radius  . 

Femur  . 

Tibia    .     .     . 

Fibula  .     .     . 

Carpus  .     . 

Metacarpus    . 

Tarsus  . 

Metatarsus 

Phalanges 

Patella  .     .     . 

Hyoid  .     .     . 

Ear.     ... 

Totals   .     . 

206 

74 

59 

73 

THE  SKELETON 


69 


sac  — - 


irregular  lines  known  as  sutures.  A  crayon  box  is  so  joined, 
but  the  teeth  in  the  wood  are  much  more  regular  than  in 
the  joints  of  the  skull. 

115.  A  Movable  Joint.  —  Let  us  take  the  knee  joint,  for 
example.  The  two  bones  which  join  are  the  femur  and  the 
tibia.  They  present  to  each  other  an  enlargement,  or  head, 
which  serves  to  increase  the  strength  of  the  joint  and  increase 
the  surfaces  applied  to  each  other.  The  two  heads  instead 
of  being  formed  altogether  of  rigid  bone  are  covered  by 
cartilage,  which  by  its  elasticity  and  smoothness  provides 
for  the  gliding  of  one  bone  upon  the  other.  Strong 
fibrous  bands  called  ligaments  bind 
together  the  ends  of  the  two  bones. 
Surrounding  the  ends  of  the  bones, 
like  a  collar,  is  found  a  liga- 
ment (the  capsular  ligament) 
inclosing  the  space  of  the 
joint  in  a  closed 
sac.  This  closed  sac 
is  called  the  capsule. 
A  thin  membranous 
sac,  called  the  syno- 
via I  membrane,  lines 
the  capsule.  It  se- 
cretes a  slimy  fluid 
which  resembles  the 
white  of  an  egg  and 
is  called  the  synovial 
fluid.  This  lubri- 
cates the  joint,  and 
is  deposited  continu- 
ally, but  only  so  fast 
as  used  up  in  exercise.  As  the  sac  has  no  opening,  air  is 
excluded,  and  atmospheric  pressure  aids  in  holding  the 
bones  in  place.  The  hip  joint  (Fig.  65)  and  other  joints 


fem,- 


isc 


FIG.  65.  — The  Right  Hip  Joint.    The  Hip  Bone 
sawed  through  so  as  to  show  the  Cup  of  the  Joint. 

fern,  femur;   acet,  cup,  or  acetabulum;   caps,  capsule; 
r.  L,  round  ligament. 


ELEMENTS   OF  PHYSIOLOGY 


have  the  same  parts  as  the  knee  joint.  It  is  rarely  that  two 
bones  put  together  so  perfectly  are  forced  from  their 
natural  places.  When  this  happens  it  is  called  a  dislocation. 

116.  The   Kinds  of    Movable  Joints   are :    the  ball-and- 
socket  joint,  which  allows  motion  in  any  direction,  as  the 
shoulder  joint ;  the  hinge  joint,  which  allows  free  motion 
back  and  forth  in  one  plane,  as  the  knee  joint ;   the  pivot 

joint,  in  which  one  bone  rotates 
around  another,  as  the  atlas 
around  the  axis,  the  radius 
around  the  ulna  (Fig.  66);  the 
gliding  joints,  in  which  the  flat 
surface  of  one  bone  glides  over 
the  other,  as  in  the  bones  of  the 
wrist ;  elastic  joints  (also  called 
mixed  joints),  in  which  there  is 
one  flexible  cartilage  growing 
to  both  bones,  and  motion  is 
allowed  by  the  compression  or 
bending  of  the  cartilage,  as 
where  the  ribs  join  the  sternum. 
Elastic  joints  are  sometimes 
called  mixed  joints,  because 
they  resemble  both  movable 
and  immovable  joints.  There 
are  about  91  hinge  joints,  4  ball- 
and-socket  joints,  only  3  pivot 
joints,  and  43  elastic  joints  in 

the  body.     The  gliding  joints  cannot  be  distinctly  divided 

and  numbered. 

117.  Structure  of  a  Long  Bone.  —  If  a  long  bone  is  sawed 
through  lengthwise  (Fig.  67),  it  will  be  observed  that  there 
is  a  central  cavity  containing  yellow  marrow.     (What  kind 
of  steak  has  a  marrow  bone  ?)    We  should  observe  also  that 
the  portions  inclosing  this  cavity  are  of  a  dense  solid  struc- 


FlG.  66.  —  The  Bones  of  the  Right 
Forearm. 

When  the  hand  is  supine  A,  and  prone 
B;  H,  humerus;  Rt  radius;  U,  ulna. 


THE   SKELETON 


ture,  but  that  the  bone  is  spongy  near  the  ends,  —  enlarged 
for  forming  the  joints.  The  cavities  in  this  spongy  por- 
tion contain  red  marrow.  A  long  bone  is  hollow,  because 
a  given  weight  of  material  has  more  strength  in  the  form 
of  a  hollow  cylinder  than  in  the  form  of  a  solid  rod.  (Does 
this  imply  that  a  hollow  cylinder  is  as  strong  as  a  solid  one 
of  the  same  size  ?) 

118.  THOUGHT  LESSON.  Classification  of  the  Movable 
Joints.  —  The  table  below  is  to  be  filled  out  by  the  same 
plan  as  in  the  Thought  Lesson  on  page  68. 


NAMES  OF  BONES 
CONNECTED 

No.  OF 
JOINTS 

BALL-AND- 
SOCKET 
JOINTS 

HINGE 
JOINTS 

GLIDING 
JOINTS 

PIVOT 
JOINTS 

ELASTIC 
OR  MIXED 
JOINTS 

Head  -atlas  .     .     . 
Atlas  -axis   . 
Rest  of  spine     . 
Ribs  -vertebrae 

I 

I 
23 

Ribs  -sternum  .     . 

Ribs  -ribs    .     .     . 

Clavicle  -sternum  . 

Scapula  -clavicle   . 
Scapula  -humerus  . 
Humerus-ulna.     . 

Humerus  -radius    . 

Wrist  joints       .     . 
Fingers    .... 
Innominate  -femur 

X 

Femur  -tibia     .     . 

Ankle      .... 

X 

Toes  

Head  -jaw    .     .     . 

Total  number    . 

141 

4 

91 

indefinite 

3 

43 

119.  Composition  of  Bone.  —  Bone  is  covered  with  peri- 
osteum. This  is  the  name  given  to  the  close-clinging 
fibrous  covering  of  the  bone,  composed  of  connective  tissue 


ELEMENTS   OF  PHYSIOLOGY 


and  blood  vessels.  If  we  remove  the  periosteum  from  the 
surface,  the  red  marrow  from  the  pores,  and  the  yellow 
marrow  from  the  larger  cavity,  we  have  remaining  the  true 
bony  substance.  Yet  even  this  is  not  one  substance,  but 
consists  of  animal  matter  and  mineral 
matter  in  the  proportion  of  two  parts  of 
the  former  to  one  of  the  latter.  The 
animal  matter  is  gelatin,  like  the  sub- 
stance composing  the  white  fibrous  part 
of  connective  tissue.  The  mineral  mat- 
ter is  chiefly  phosphate  of  lime  and 
carbonate  of  lime.  Can  you  describe 
the  microscopic  structure  of  bony  tis- 
sue as  shown  in  Fig.  70?  The  mineral 
matter  may  be  removed  by  soaking  the 
bones  for  several  days  in  strong  vinegar  or 
in  dilute  muriatic  acid.  The  bone  is  then 

flexible  but  tough. 

If  a  slender  bone, 

as  a  hog's  rib,  has 

been   used,  it  can 

be  tied  in  a  knot; 

after  the  acid  has 

been  washed  off,  it  FlG.  67.  -  shin-bone 

may  be  preserved      <tibia)  sawed  in  two 

in  dilute  alcohol  as 

a   curiosity.      The 

animal  matter  may 

be     removed     by 

FIG.    68.  — Side    and    Under    holding    the     bone 
View  of  a  Vertebra.  i    .       , , 

on  a  shovel  in  the 

Is  it  a  cervical,  a  thoracic,  or  alum-  r  __     .  ..  .         ..      . 

bar  vertebra?     (See  Fig.  69.)        fire    for    a    Sufficient    length    of    time. 

The  mineral  part  remaining  is  very 

light  and  brittle,  and  weighs  only  one  third  as  much  as  the 
original  bone,  the  form  of  which  it  still  preserves. 


along  its  Length. 

2,  struts  and  stays  of 
spongy  bone  support- 
ing 7,  the  upper  and 
lower  articular  sur- 
faces; 3,  compact  bone 
forming  the  shaft  ; 
4,  marrow  cavity  ; 
6,  periosteum. 


THE   SKELETON 


73 


120.    THOUGHT  LESSON.    The  Spinal     0 
Column.  — 

1.  Observe  a  single  vertebra(Fig.  68). 
What  is  the  use  of  the  "body  "of  a  ver- 
tebra? the  arch?  the  processes? 

2.  How  is  the   spinal  column  con-     ^ 
structed    so    as   to    allow    movement 
(Fig.  69),  without  seriously  displacing 
any  organ  supported  by  it  ? 

3.  In  the  general  form  of  the  spinal 
column  what  shows  that  its  strength 
is  proportional   to    the    weight   to  be 
supported  (Fig.  69)? 

4.  Do  the  spinous  (or  rear  processes) 
project  at  the  same  angle  in  all  parts 
of  the  spinal  column  (Fig.  69)  ? 

5.  Find,  by  bending  your  own  body,    L. 
or  by  studying  Figure  69,  what  part 
allows  least  motion.     Why  ? 

6.  Why  are   the   spinous  processes 
a  source  of  danger  to  the  spinal  cord, 
instead  of  a  protection  ?    (Suggestion  : 
a  blow  from  the  rear,  or  a  fall  upon  a 
process,  would  cause  what  part  of  a 
vertebra  to  break  ?  ) 

7.  In   what   region    might    a    blow 
from  the  rear,  or  a  fall,  cause  the  pro- 
cess to  snap  off   and    leave  the  cord 
uninjured  ? 

8.  If  the  processes  inclined  in  the  FIG.  69.  —The  Vertebral 
neck  and  the    lumbar   regions,  as   in 

the  thoracic  region,  what  disadvantage 

WOUld  there  be  ? 

9.  Which  part  of  the  spinal  column 
is  most  easily  sprained  ?     Which  next  ? 


'  £  «£ 

dorsal,  or  thoracic;  L,  first 
lumbar  vertebra  ;  S,  sacrum; 

c,  Coccyx  ;   sp,  spinous 
*'  transvcr$e 


74 


ELEMENTS   OF  PHYSIOLOGY 


HYGIENE  OF  SKELETON 

121.  Nourishment  of  Bones.  —  If  a  limb  be  disused  be- 
cause of  paralysis  or  long  sickness,  the  bones,  as  well  as 
the  soft  parts,  lose  in  strength  and  weight.  This  shows 
that  the  more  vigorous  circulation  which  comes  with  exer- 
cise helps  to  repair  the  osseous  tis- 
sue (Fig.  70).  The  blood  vessels 
that  supply  the  bones  enter  from 
the  inner  side  of  the  periosteum. 
We  thus  see  why  the  bone  shrinks 
away  if  the  periosteum  is  removed, 
and  why  the  surgeon  is  careful  to 
leave  as  much  of  the  periosteum  as 
possible  in  the  case  of  bones  splin- 
tered by  accidents. 

The  animal  matter  of  bones  is 
most  abundant  in  childhood,  and 
a  child's  bones  will  bend  before 
they  break.  If  broken,  they  heal 
rapidly.  The  animal  matter  is  less 
abundant  in  the  aged,  therefore 
the  bones  are  brittle,  more  easily 
broken,  and  take  longer  to  heal. 

122.  Broken  Bones.  —  The  two 
ends  of  a  broken  bone  should  be 
brought  together  in  their  correct 
position  as  soon  as  possible,  before 
inflammation  and  swelling  render 
this  difficult.  Of  course  a  surgeon  should  be  called  to  set 
a  broken  bone.  If  the  patient  has  to  be  carried  some  dis- 
tance, care  should  be  taken  to  prevent  injury  to  the  fleshy 
parts  by  the  ends  of  the  fractured  bone ;  the  limb  should 
be  bound  with  handkerchiefs  to  a  strip  of  board,  or  even 
to  umbrellas  or  walking  sticks,  as  temporary  splints 


FIG.  70.  —  Haversian  Canals  in 
Compact  Tissue  of  Bones, 
with  their  Connecting  Cana- 
liculi  and  the  Lacunae.  Mag- 
nified 200  Diameters. 

The  bone  is  cut  lengthwise.  Com- 
pare with  Fig.  44  where  the  bone 
is  shown  cut  across  ;  why  are 
fewer  canaliculi  cut  apart  in  Fig. 
44  than  in  Fig.  70? 


THE   SKELETON* 


75 


123.  Dislocation   of   a    joint    stretches    and    sometimes 
breaks  the  ligaments  surrounding  it,  producing  inflamma- 
tion.    This  makes  examination  of  it  difficult,  hence  there 
should  be  no  delay  in  procuring  the  necessary  skill  and 
restoring  it  to  place. 

124.  A  Sprain  is  an  injury  due  to  a  sudden  wrenching  or 
straining  of  the  ligaments,  as  a  result  of  which  a  ligament 
is  lacerated  or  torn  from  its 

fastenings  to  the  bone.  A 
bad  sprain  may  be  more  seri- 
ous than  a  fracture,  and  result 
in  stiffness  or  in  permanent 
weakness.  Immediate  rest  is 
necessary.  A  hot  footbath 
immediately  after  spraining 
the  ankle  is  sometimes  bene- 
ficial; careful  rubbing,  very 
light  at  first  and  gradually  in- 
creasing in  vigor  from  day  to 
day,  may  shorten  the  period 
of  recovery. 

125.  Acquired    Deformities. 
— The  bones   are  flexible   in 
childhood,    and,    in    the    case 

Of    Children     at     School,     Seated      A  position  conducive  to  round  shoulders. 

so  that  the  feet  hang,  instead 

of  resting  upon  the  floor,  the  thigh  bones  may  become 
bent  by  the  weight  of  the  legs  below.  Bowlegs  are 
caused  by  encouraging  children  to  walk  while  too  young. 
The  bones  of  the  feet  are  deformed  by  tight  shoes,  "  flat 
foot "  sometimes  resulting ;  but  most  often  the  toes  only 
are  deformed,  the  joint  at  the  base  of  the  big  toe  be- 
coming enlarged  into  an  unsightly  bump.  Tight  shoes  by 
influencing  the  gait  may  hinder  the  development  of  the 
body. 


FIG.  71.  — Sitting  with  Head  and 
Shoulders  drooped  forward  at 
Work. 


76  ELEMENTS   OF  PHYSIOLOGY 

126.  Deformities  of  the  Spinal  Column  come  chiefly  on 
account  of  the  yielding  nature  of  the  cartilage.  The  ex- 
tent of  the  compressibility  of  cartilage  may  be  realized  if 
one's  height  is  measured  upon  rising  in  the  morning  and 
again  at  night,  when  the  loss  in  height  sometimes  amounts 
to  nearly  half  an  inch.  The  cartilages  between  the  verte- 
brae are  very  thick,  so  as  to  give  flexibility  to  the  spinal 
column.  This  blessing  also  brings  with  it  a  danger  of 
deformity.  If  the  head  is  bent  forward  continuously  in 
study  or  work  instead  of  being  held  up  (Fig.  71),  the 

upper   cartilages    are   compressed   in 

front,    the   ligaments    stretch,   and    a 

f  deformity  of  the  neck  may  result,  caus- 

ing the  head  to  project  forward. 
Working  with  the  desk  low  in  front, 
or  working  upon  the  ground,  may 
cause  round  shoulders. 

127.    Tight    clothing    deforms    the 
ribs,   which    are  readily  movable  be- 

Writing  at  a  desk  that  is  too  r        ,  ,  .,  .-p.. 

high  causes  one  shoulder  cause  of  the  long  cartilages.  The 
binding  down  of  the  front  ends  of 
the  ribs  causes  posterior  curvature  of 
the  spine,  with  flat  chest  and  round  shoulders.  Lateral, 
or  sidewise,  curvature  of  the  spine  is  caused  by  constantly 
carrying  the  book,  satchel,  or  other  weight  in  the  same 
hand ;  by  overindulgence  in  the  valuable  habit  of  horse- 
back riding  (in  the  case  of  ladies) ;  by  writing  at  a  desk 
that  is  too  high  (Fig.  72);  by  hanging  the  head  to  one 
side. 

128.  Posterior  curvature  is  caused  by  habitually  bending 
over  the  work,  and  by  slipping  down  in  the  seat  or  desk 
(Fig.  73).  (It  has  been  called  "  trying  to  sit  upon  the  small 
of  the  back.")  It  is  caused  also  by  weakness  of  muscles, 
by  wearing  shoes  with  high  heels,  and  by  writing  at  a  desk 
that  is  too  low.  In  curvature  of  the  spine,  the  cartilages 


THE  SKELETON 


77 


become  V-shaped,  and  the  ligaments  stretched.  If  shoulder 
braces  are  so  uncomfortable  as  to  serve  as  a  reminder  every 
time  the  wearer  drops  back  into  the  old  position,  can  they 
do  good  ?  If  they  comfortably  support  the  trunk  so  as 
to  take  the  weight  off  the  muscles,  do  they  do  good  or 
harm  ?  If  it  takes  some  months  to  compress  the  cartilages 


FIG.  73. 

Flat  chest,  protruding  chin,  and  round 
shoulders  are  produced  by  slipping 
forward  on  the  seat. 


FIG.  74. —  The  Proper  Position 
in  Sitting. 

This  position  is  also  the  easiest  be- 
cause the  weight  is  poised. 


and  stretch  the  ligaments,  thus  deforming  the  spinal  col- 
umn, should  one  expect  to  recover  natural  grace  of  form 
in  a  few  days  ?  Exercise  of  the  neglected  muscles,  that  is, 
opposite  muscles,  instead  of  those  that  were  used  exces- 
sively while  acquiring  the  deformity,  is  a  great  aid. 
Posterior  curvature  has  been  overcome  by  sleeping  on  the 
back  on  the  floor,  or  on  a  hard  mattress. 

129.  The  Rule  for  Correct  Position  in  sitting  is  to  sit  back 
in  the  chair  with  body  and  head  erect  (Fig.  74).  The 
correct  position  in  standing  or  walking  is :  chest  forward, 


ELEMENTS   OF  PHYSIOLOGY 


chin  in,  hips  back.  By  keeping  this  attitude  in  mind  and 
practicing  it  faithfully  for  a  few  weeks,  one  can  train  the 
muscular  sense  to  become  so  accustomed  to  it  that  a  stoop- 


FlGS.  75,  76,  77.  —  Positions  in  Standing.     (After  Mosher.) 

In  Fig.  75  the  weight  rests  equally  upon  both  legs.  This  position  does  not  cause  deformity, 
but  soon  becomes  tiresome,  as  the  legs  demand  the  privilege  of  working  by  turns. 

In  Fig.  76  is  shown  the  best  position  and  the  one  that  should  be  assumed  habitually.  One 
foot  is  slightly  advanced,  and  the  weight  of  the  trunk  can  be  transferred  with  ease  from 
one  leg  to  another.  The  chest  is  free  to  expand. 

In  Fig.  77,  one  leg  supports  the  trunk  and  the  other  is  thrown  to  one  side  as  a  brace.  It 
is  very  harmful  if  the  weight  is  not  often  shifted.  One  who  has  acquired  the  habit  of 
dropping  upon  one  and  the  same  leg  while  at  work  soon  shows  the  following  variations  from 
the  normal  :  — 

If  it  is  the  right  leg,  for  instance,  that  supports  the  body,  the  right  thigh  becomes  greater  in 
circumference,  the  right  hip  higher,  the  spinal  column  curved  laterally  with  concave  side  to 
the  right.  The  right  shoulder  is  lower  than  the  left,  the  ribs  are  crowded  together  on  the 
right  side,  the  face  becomes  slightly  unsymmetrical. 


ing  or  crooked  position  will  be  uncomfortable  (Figs.  75,  76, 

77,  78,  79> 

130.  Nutrition  of  Bones.  —  Good  food  and  pure  air 
brought  by  a  vigorous  circulation  are  necessary  to  the 
health  of  the  bones.  Poor  or  indigestible  food,  stimu- 


THE   SKELETON 


79 


lants,  and  poisons  affect  the  health  and  strength  of  the 
bones.      Surgeons  report  cases  of  fracture  of   the  bones 

occurring  in  persons   having 

the  alcohol  habit,  where  the 

bones    would    not    unite    by 

bony  material,  but  remained 

flexible  and  useless.     Indul- 
gence   in    alcoholic    liquors, 

especially    wine,    is    a    very 

prominent  feature   in  the 

causation  of  gout,  a  disease  of 

the  joints.    Tendency  to  gout 

may  be  inherited.     Smoking 

in   boyhood  often   results  in 

low     and     stunted     stature. 

Rheumatism  of  the  joints,  a 

diseased   condition   in  which 

acids     accumulate,    affecting 

the  nerves  very  painfully,  is 
FIG.  78  — Tncor-  sometimes  caused  by  chronic 
rect  Position  in  indigestion,  which  in  turn  may 

Standing.  ,  •,  •,  ,  ,          r  This  would  be  correct 

have  been  brought  on  by  fre-      if  the  body  were 
quent  taking  of  drugs,  by  want  of  exercise, 
or  by  other  causes. 

131.  THOUGHT  LESSON.  The  Joints  of 
the  Arms  (Figs.  61  and  66). —  The  arm  is 
for  grasping  and  for  moving  things.  In  order  to  perform 
this  function,  the  joints  are  so  located  and  arranged  as  to 
give  to  the  movements  of  the  arm  the  utmost  possible 
accuracy,  range,  firmness,  and  delicacy. 

'  i.  Determine  which  of  the  above  four  qualities  predomi- 
nates in  different  joints,  as  follows :  The  ball-and-socket 
joint  gives  -  -  to  the  arm  movements.  The  hinge  joint 
gives to  the  arm  movements.  The  pivot  and  glid- 
ing joints  give and to  the  movements. 


FIG.  79. 


not  apparently  too 
strained  and  stiff. 
Compare  positions 
of  head,  chest,  and 
hips  in  Figs.  78 
and  79. 


80  ELEMENTS   OF  PHYSIOLOGY 

2.  Why  is  it  better  to  have  a  ball-and-socket  joint  at  the 
shoulder  and  a  hinge  joint  at  the  elbow,  rather  than  vice 
versa  (Fig.  49)? 

3.  What   economy  of   motion  is   there   in  having  the 
pivot  joint  in  the  forearm  rather  than  at  the  shoulder? 


APPLIED   ANATOMY 
EXERCISE    I 

1.  What  in  the  composition  of  a  bone  gives  it  stiffness?  hardness? 
toughness?  flexibility? 

2.  Should  chairs  and  benches  have  straight  backs? 

3.  Why  is  a  chair  back  that  is  very  slanting  often  injurious?     Why 
is  a  very  deep  chair  injurious,  if  deep  enough  for  the  front  edge  to  strike 
the  occupant  behind  the  knee? 

4.  Why  does  a  young  child  usually  crawl  before  it  walks? 

5.  Which  girdle  is  attached  directly  to  the  spinal  column?    Which 
girdle  is  attached  indirectly? 

6.  Why  is  the  arm  so  often  dislocated  at  the  shoulder? 

7.  High  pillows  may  cause  what  deformity? 

8.  Which  three  bones  in  the  body  are  not  attached  to  other  bones? 
Find  twenty-seven  bones  in  the  skeleton  which  are  attached  to  other 
bones  at  one  end,  but  have  the  one  end  free  (Fig.  49) . 

9.  Why  does  a  fall  not  hurt  a  child  as  much  as  it  does  an  adult? 

10.  Should  a  young  child  be  urged  to  stand  or  walk? 

11.  What  part  of  a  long  bone  is  composed  of  compact  tissue?    Of 
very  porous  tissue  ? 

EXERCISE   H 

12.  Could  the  neck  be  broken  and  death  result  without  breaking 
a  bone? 

13.  What  would  be  the  result  if  the  ligaments  were  composed  of  the 
yellow  fibers  of  connective  tissue  instead  of  the  white  fibers  (Fig.  32)  ? 

14.  If  a  child's  feet  be  allowed  to  dangle  from  a  high  seat,  what 
will  be  the  effect?     (See  §  125  ;  also  Chapter  VIII,  on  Circulation.) 

15.  Is  the  ''straight  front"  a  healthful  position? 

1 6.  The  pivot  joint  formed  by  the  peg  of  the  axis  projecting  into  the 
atlas  allows  the  head  to  rotate  through  a  large  part  (about  half)  of  a 
circle.     Can  it  nod  in  any  position  in  that  half-circle  ? 


THE   SKELETON  8 1 

17.  When  the  palm  is  turned  upward  is  the  radius  parallel  or  crossed 
with  the  ulna?     When  the  back  of  the  hand  is  up? 

1 8.  Why  should  one  always  sit  and  walk  erect? 

19.  What  are  the  only  two  vertebrae  whose  surfaces  move  upon  each 
other?    How  is  motion  between  the  other  vertebrae  accomplished? 

20.  In  a  long  bone  what  is  chiefly  a  storage  tissue,  saving  food  for 
future  use?     (§117.) 

21.  Ligaments  are  of  very  slow  growth.     This  accounts  for  the 
tedious  nature  of  the  recovery  from  what  kind  of  accidents  ? 

22.  Observe  how  many  of  your  classmates   sit  "slid  forward"  in 
the  seat,  and  report  in  recitation  the  result  of  your  count. 

23.  When  the  school  is  marching  out,  count  those  who  walk  with 
the  head  protruded. 

24.  A  bone  felon  is  often  caused  by  a  bruise  on  the  bone  beneath 
the  periosteum.     Why  should  it  be  lanced? 


CHAPTER  VII 
THE  CIRCULATION 

132.  Function   and  Composition   of  Blood.  —  It  will   be 
recalled  that  the  tissues  composing  the  body  are  made  up 
of  cells ;  that  these  cells  are  active  and  must  have  food ; 
that  there  are  several  substances  necessary  to  feed  the 
cells  (albumin,  fat,  sugar,  water,  salt,  lime);  that  some  of 
these  substances  undergo  slow  combustion  in  the  tissues ; 
that  this  combustion   or  uniting  with   oxygen   gives  rise 
to  carbon  dioxid    and  other  waste  substances.      How  is 
the  food  taken  to  the  cells,  how  does  the  oxygen  reach 
them,  and  how  are  the  products  of  combustion  removed 
before  they  accumulate  and  do  injury  to  the  delicate  cells  ? 
These  three  things   are  done  by  the   circulation  of  the 
blood.     We  can  thus  readily  see  how  important  the  blood 
is  and  how,    if   the   circulation   is   free   and   strong   and 
reaches  every  part  of  the  body,  it  is  almost  impossible  for 
disease  and  weakness  to  occur  in  the  body. 

133.  Assist,  in  imagination,  in  an  experiment  of  great 
interest.     The  artery  of  a  hog  or  other  animal  is  opened. 
As  the  blood  escapes  the  animal  weakens ;  at  last  it  suc- 
cumbs, and  lies  motionless,  insensible,  without  breathing, 
without  any  external  sign  of  life.     It  is  only  a  carcass  in 
appearance ;  and  in  a  few  seconds,  it  will  be  only  a  carcass 
in  reality.     Its  life  is  arrested  and  will  soon  be  finished 
for  want  of  combustion  in  the  body  excited  by  oxygenated 
blood.      Without   delay,    the  extracted   blood   is   injected 
again  into  the  veins  of  the  animal.     If  the  experiment  is 
conducted  by  skillful  hands,  you  will  now  assist,  as  it  were, 

82 


THE   CIRCULATION 


at  a  resurrection.  The  body  seems  to  move,  little  by  little 
strength  returns,  and  finally  the  animal  rises.  The  life  has 
returned  because  the  vital  combustion,  not  totally  extin- 
guished, was  resumed  when  the  blood  reentered  the  vessels. 

134.  It  is  found  that  the  heart  stops  beating,  or  beats 
very  faintly,  just  before  a  person  faints.     What  does  this 
show  to  be  constantly  needed  that  the  mind  may  work  ? 

Give  a  proof  that  blood  is  present  almost  everywhere  in 
the  body. 

Explain  why  blushing  is  a  proof  of  this  fact  ?  What  two 
kinds  of  tissue  are  destitute  of  blood  vessels  (Chapter  II)? 

135.  The  Problems,   the  answers  to  which    we   are   to 
study  in  this  chapter,  are :  the  composition  of  blood,  the 
reasons  for  this  composition,  and  how  the  blood   is   dis- 
tributed to  the  different  cells  and  tissues. 

136.  Composition  of  the  Blood.  —  When  seen  under  the 
microscope   blood   no   longer  appears  of  a   uniform   red 
color.    It  is  found  to  con- 
sist of  a  clear,  colorless 

liquid  called  plasma,  in 
which  floats  a  multitude 
of  small  bodies  called  cor- 
puscles. The  corpuscles 
themselves  are  seen  to  be 
of  two  kinds.  By  far  the 
greater  number  are  round, 
yellow,  and  flattened,  but 
a  few,  perhaps  one  in  four 
hundred,  are  round,  white, 
and  globular,  and  larger  than  the  yellow  ones  (Fig.  80). 
The  yellow  ones  are  called  the  red  corpuscles,  because  the 
light  shining  through  a  great  number  of  them  gives  the 
blood  a  red  color. 

137.  Reasons  for  the  Composition  of  the   Blood. —  That 
the  blood  may  flow  readily  through   every  little  tube,  it 


FIG.  80. 

B,  red  corpuscles  seen  from  the  side ;  D,  red  cor- 
puscles, seen  on  edge,  are  run  together  in  rows; 
G,  F,  colorless  corpuscles. 


84  ELEMENTS   OF  PHYSIOLOGY 

must  be  liquid,  hence  a  large  part  of  it  is  water.  It  is  the 
plasma  or  watery  portion  of  the  blood  which  transports 
the  food  to  the  tissues.  The  plasma  is  not,  then,  a  simple 
but  a  very  complex  liquid.  The  tissues  require  albumin, 
fat,  sugar,  and  mineral  food.  We  should  expect  the  plasma 
to  contain  all  of  them,  and  so  it  does.  As  we  should  like- 
wise expect,  it  gets  this  nourishment  from  the  alimentary 
canal.  The  sugar  is  in  the  form  of  grape  sugar,  and  be- 
cause of  this,  blood  or  meat  containing  it  is  slightly  sweetish 
in  taste.  The  fat  is  in  the  form  of  minute  globules,  and 
the  albumin  is  similar  to  egg  albumen,  but  very  much 
diluted  with  water. 

138.  Let  us  take  up  another  function  of  the  blood.  How 
does  it  carry  the  oxygen  ?  This  gas  enters  the  red  cor- 
puscles while  the  blood  is  in  the  lungs,  and  makes  them  a 
brighter  red.  It  is  given  up  to  the  tissues ;  and  at  the  same 
time  the  tissues  give  up  carbon  dioxid,  which  is  carried  to 
the  lungs  by  the  corpuscles  and  the  plasma.  YtTe  liquid 
impurities  in  the  tissues  are  carried  by  the  plasma  to  the 

j skin  and  kidneys.     We  see,  then,  that  the 

i  Jj  red  corpuscles  transport  the  greater  part 

of    gaseous    material,    while    the    plasma 
I     ^Hak     transports  the  liquids  and  the  solid  mate- 
mm  fl    H    r^s  dissolved  m  the  liquids. 

139.   What  are  the  White  Corpuscles  for? 

\^&/       -This  brings  us  to  a  fourth  function  or 

FIG  81  use  °f  tne  blood,  a  function  that  has  been 

i,  human  blood  cor-  discovered  only  within  the  last  few  years. 

fronfvkwf t  fro"*  The  blood  of  healthy  persons  possesses  a 

biood  corpuscles,  certain  power  of  destroying  germs  of  dis- 

side  and  front  view.  •'        °    c 

Both  are  drawn  to  ease  which  may  enter  the  body;    this  is 

the  same  scale.  -  .    . 

called  its  germicidal  or  germ-killing  power. 
The  germs  are  minute  one-celled  organisms  to  be  seen 
only  through  a  powerful  microscope.  Some  float  in  air ; 
others  are  found  in  liquids  or  solids.  Most  kinds  of  germs 


THE   CIRCULATION 


are  not  harmful  to  man.  For  instance,  there  is  a  germ 
which  gets  into  milk  and  causes  it  to  turn  sour.  The 
yeast  germ,  used  in  bread  making,  is  a  microscopic  one- 
celled  plant  which  obtains  its  nourishment  from  sugar. 

140.  The  germicidal  power  of  the  blood  is  believed  by 
many  physiologists  to  rest,  in  part  at  least,  in  the  white 

corpuscles.     When  the  flesh  

is  cut,  or  when  bacteria  lodge 

in  the  tissues,  these  little 
scavengers  may  be  seen 
collecting  at  the  danger 
point  in  great  numbers: 
some  of  the  germs  are  de- 
voured bodily  by  the  white 
corpuscles :  others  are  killed 
probably  by  substances  in 
the  plasma  which  were 
formed  by  these  little  guardi- 
ans. In  no  way  is  the  provi- 
sion for  our  welfare  better 
shown  than  by  the  existence 
of  these  corpuscles  (Fig.  82). 

141.  Experiment    on    the 
Parts    of    the    Blood.  —  If 
some  blood  from  an  animal 
is  allowed  to  stand  in  a  ves- 
sel, it  soon  becomes  a  red, 
jelly  like  mass.    This  change 

is  called  coagulation.  If  we  let  the  coagulated  blood  stand, 
it  gradually  separates  into  two  parts,  —  a  light  yellow  liquid 
called  serum,  which  is  colored  by  a  few  blood  cells,  and  a 
semi-solid  mass  called  the  clot,  which  contains  most  of 
the  cells  together  with  some  threadlike  fibers  (Fig.  83). 
A  substance  called  animal  fibrin  was  in  solution  in  the 
plasma  or  liquid  portion  of  the  blood.  It  has  solidified 


FIG.  82.—  Migration  of  White  Corpuscles 
through  the  Walls  of  a  Vein. 

They  are  shown  in  different  stages  of  migra- 
tion. The  red  corpuscles  remain  in  the 
stream. 


86 


ELEMENTS   OF  PHYSIOLOGY 


into  fibers  which  by  entangling  the  corpuscles  caused  the 
formation  of  the  clot.  The  serum,  or  the  portion  of  the 
blood  that  remains  liquid,  is  composed  of  water  and  albu- 
min, with  traces  of  sugar,  fat,  and  certain  salts.  If  the 


FlG.  83.  —  Diagram  to  Illustrate  the  Process  of  Coagulation. 

I.     Fresh.  II.     Coagulating.  III.     Coagulated. 

(Corpuscles  and  plasma.)  (Birth  of  fibrin.)  (Clot  and  serum.) 

Plasma  minus  fibrinogen  equals  serum.     Corpuscles  plus  fibrin  equal  clot. 

water  is  -boiled  away,  the  albumin  is  left  as  a  white  jelly. 
The  composition  of  the  clot,  serum,  and  plasma  may 
be  shown  as  follows  :  — 


COAGULATED  I 

BLOOD 

I  Serum 


(  Blood  corpuscles 
1  Fibrin 

J  Water       J>  Plasma 
1  Albumin 


LIQUID 
BLOOD 


CIRCULATION  OF  THE  BLOOD 

142.  The  organ  which  gives  the  push  or  impulse  to  the 
blood  and  causes  it  to  circulate  in  the  tubes  or  vessels  is 
the  heart  (Fig.  84).  The  tubes  that  conduct  the  blood 
away  from  the  heart  to  the  organs  and  tissues  are  called 
arteries.  The  tubes  through  which  it  returns  to  the  heart 
are  called  veins.  The  very  small  tubes  that  take  the  blood 
from  the  arteries  to  the  veins  where  it  begins  its  return 
journey  are  called  capillaries.  The  blood  must  circulate  in 
order  that  it  may  go  to  the  digestive  organs  to  get  food, 
to  the  lungs  to  get  oxygen,  and  to  all  the  tissues  in  order  to 
distribute  these  things,  and  to  carry  away  waste  materials 
to  the  organs  that  will  free  the  body  of  them.  Can  you 
see  in  your  mind  the  dark  color  of  a  piece  of  beef  and 


THE   CIRCULATION 


the  lighter  color  where  a  fresh  cut  is  made  ?  Blood 
going  from  the  lungs  to  the  tissues  is  bright  red,  about 
the  color  of  a  piece  of  new  beef  when  the  knife  cuts  into 
it.  The  blood  going  from  the  tissues  to  the  lungs  is 
darker,  about  the  color  of  the  outside  of  the  piece  of  raw 
beef  some  time  after  it  is  cut. 

143.  The  heart  is  situated  in  the  chest,  between  the  two 
lungs.     It  is  a  hollow  muscle,  and    has   the   remarkable 
power  of  contracting  and  relaxing  itself  with  periodical 
regularity.     The   movement  of  contraction  is  called   the 
systole  ;  the  relaxation  is  called  the  diastole. 

144.  The  heart  is   divided  by  a  vertical  partition  into 
halves  (Fig.  84).     The  right  half  receives  the  dark  blood 


PULMONARY 


FIG.  84.  — Diagrammatic  Section  of  Heart. 

from  the  body  and  sends  it  to  the  lungs.  The  left  half 
receives  the  bright  blood  from  the  lungs  and  sends  it  to 
every  part  of  the  body.  Each  half  is  also  divided  by  a 
horizontal  partition,  but  unlike  the  vertical  ones,  these  par- 
titions are  pierced  with  openings  for  communication.  The 
heart  therefore  contains  four  chambers  ;  the  two  upper 
ones  are  called  auricles,  the  two  lower  ones  ventricles. 
The  right  auricle  communicates  with  the  right  ventricle  just 


88 


ELEMENTS   OF  PHYSIOLOGY 


pulmonary 
veins 


pulmonary 
veins 


below  it,  and  the  left  auricle  communicates  with  the  left 

ventricle. 

145.   Circulation  of  the  Blood.  —  From  all  parts  of  the 

body  (except  the  lungs)  the  blood   arrives  at  the   right 

auricle,  dark  red  in  color, 
and  charged  with  carbon 
dioxid,  a  gas  that  is  unfit 
for  supporting  life.  The 
blood  has  come  through 
two  large  veins,  the  supe- 
rior vena  cava,  from  the 
head,  arms,  etc.  (Fig.  85), 
and  the  inferior  vena  cava, 
from  the  lower  parts  of 
the  body.  The  first  cham- 
ber of  the  heart  that  it 
enters  is  the  right  auricle. 
The  auricle  contracts  and 
presses  the  blood  into  the 
right  ventricle  (Fig.  86). 

FIG.  85.- Diagram  tTthow  the  Course  of  the    Jt    beSins    tO    Squeeze    tO- 

Biood  through  the  Heart.  gether    just    around    the 

The  vessels  containing  impure  blood  are  drawn    openings    of    the  VCinS,   SO 
darker  than  the  others. 

that  it  closes  their  open- 
ings. The  blood,  owing  to  this,  cannot  go  back  into  the 
veins,  but  is  forced  into  the  ventricle.  The  right  ventricle 
thus  filled  with  blood  at  once  begins  to  contract.  The  first 
effect  of  the  pressure  thus  produced  is  to  force  blood  behind 
the  flaps  of  the  tricuspid  valve,  the  valve  between  the  auri- 
cle and  ventricle,  consisting  of  three  flaps  made  of  white 
fibrous  tissue.  The  blood  behind  the  flaps  brings  the  flaps 
together  and  so  blocks  the  way  to  the  auricle  (Fig.  87). 
The  contraction  of  the  ventricle  goes  on,  and  soon  the 
blood  presses  hard  enough  upon  the  semilunar  valve  to 
open  it  and  go  on  into  the  pulmonary  artery  (Fig.  85); 


THE    CIRCULATION  89 

the  pressure  from  the  ventricle  soon  sends  it  through  the 
swollen  artery  into  the  lungs  (Plates  IV  and  VIII). 

146.  When  the  ventricle 
has  emptied  itself,  it  re- 
laxes. The  semilunar  valve 
is  composed  of  three  pock- 
ets, which  the  swollen  pul- 
monary artery  fills  with 
blood  as  soon  as  the  ventri- 
cle begins  to  relax.  The 
pockets  of  the  valve  are 
thus  pressed  together,  and  FIG.  87.— The  Blood 

FIG.  86.  —  The  Right  -,  ,        i     n  i        i  going  through  the 

Side  of  the  Heart.      HO    blood    flows    back    into        Pulmonary  Artery 

The  blood  flowing  the  ventricle.     The  auricle     to  the  Lungs. 

through    the   tricus-  ..        .  .    ..         .  Trictisnid  valve  closed 

pid  valve  into  the  was  relaxing  while  the  ven-  Tnsce^fj^e  ^s 

tricle  was  contracting,  and      °Pen- 

it  is  already  filled  with  blood  that  has  flowed  in  from  the 
veins.  After  a  short  pause,  it  again  contracts ;  and  the 
same  action  is  repeated.  More  and  more  blood  is  thus 
driven  by  the  right  ventricle  through  the  semilunar  valve 
into  the  pulmonary  artery,  so  that  the  blood  which  is 
already  in  the  artery  is  sent  on  through  the  numerous 
small  branches  and  through  the  multitude  of  fine  tubes 
called  capillaries ',  which  go  through  every  part  of  the  lungs. 

147.  In  the  lungs  the  carbon  dioxid  passes  into  the  air 
passages,  and  the  oxygen  brought  by»the  breath  goes  into 
the  blood  of  the  capillaries,  which  changes  in  color  to 
bright  red.  The  capillaries  unite  again  to  form  the  pul- 
monary veins,  which  lead  back  to  the  heart.  We  thus 
see  how  the  blood  is  sent  from  the  heart  through  the 
lungs  and  back  to  the  heart.  How  is  the  blood  sent  through 
the  body  and  back  to  the  heart  ?  We  shall  find  that  this 
is  done  by  the  left  side  of  the  heart;  that  the  two  pumps 
work  in  unison ;  that,  in  fact,  a  wave  of  muscular  contrac- 
tion starting  at  the  top  of  the  heart  passes  downward  over 


90  ELEMENTS   OF  PHYSIOLOGY 

both  sides  of  the  heart  at  once,  both  auricles  contracting 
at  the  same  time  and  then  relaxing  as  the  contraction 
passes  to  the  ventricles. 

148.  As  we  learned,  the  pressure  from  the  right  ventricle 
keeps  the  blood  moving  through  the  pulmonary  artery,  the 
capillaries  of  the  lungs,  and  the  pulmonary  vein ;  it  returns 
to  the  heart  again,  and  this  time  it  enters  the  left  auricle. 

149.  When  the  left  auricle  is  full,  it  contracts  and  drives 


m.v.a 


MAY 

FIG.  88.  —  View  of  the  Orifices  and  Valves  of  the  Heart  from  below,  the  whole  of 
the  two  Ventricles  being  cut  away. 

Ao,  aorta;  PA,  pulmonary  artery,  each  with  its  three  cups  of  the  closed  semilunar  valves 
seen  convex  from  below;  RAVt  opening  between  right  auricle  and  right  ventricle, 
surrounded  by  the  three  flaps,  t.v.i,  t.v.-z,  t  ^.3,  of  the  tricuspid  valve  with  chordae  tendineae 
between  them,  to  which  three  cords  are  tied,  taking  the  place  of  the  papillary  muscles; 
LA  V,  opening  between  left  auricle  and  left  ventricle,  with  the  two  flaps,  m.-v.  i,  m.v.  z 
of  the  mitral  valves  and  chordae  tendinae,  to  which  cords  are  tied. 

This  figure  may  be  said  to  show  the  roof  of  the  two  ventricles,  with  the  two  great  valves 
by  which  the  blood  enters  the  ventricles  and  the  two  great  valves  by  which  it  leaves  them. 
All  the  openings  of  the  ventricles  are  upward. 

the  blood  through  a  valve  called  the  bicuspid  (Fig.  88), 
or  mitral,  valve,  into  the  left  ventricle.  [Mnemonic :  the 
t(r)i  cuspid  is  on  the  (r)ight  side,  the  bicuspid  on  the  left.] 
The  left  ventricle  (at  the  same  time  with  its  mate,  the  right 
ventricle)  then  contracts,  forcing  the  blood  behind  the  flaps 


THE   CIRCULATION 


of  the  bicuspid  valve,  closing  the  way  back  to  the  left  au- 
ricle. The  pressure  of  the  ventricle  opens  the  semilunar 
valve  in  the  mouth  of  the  great  aorta,  which  is  the  large 
artery  carrying  the  blood  from  the  left  ventricle.  The 
aorta  takes  the  blood  to  every  part  of  the  body  except  the 
lungs.  It  gives  off  smaller  arteries,  and  the  division  is 
repeated  until  arteries  are  supplied  to  every  organ  and  tis- 
sue. In  the  tissues  the  arteries 
empty  into  smaller  tubes  called 
capillaries.  The  aorta,  with  its 
branches,  becomes  distended  with 
blood,  and  as  more  and  more  is 
forced  into  it  by  the  left  ventricle 
at  each  heart  beat,  the  distention  is 
kept  up,  and  some  of  the  blood 
already  in  the  aorta  is  forced  along 
its  branches,  and  the  same  pressure 
forces  it  through  the  capillaries  and 
into  the  veins  (Plates  V  and  VIII). 

150.  The     blood     flows     slowly 
through   the   capillaries    and    per- 
forms its    function  of    exchanging 
substances  needed  for  those  used 
up.     It  next  goes  into  the  veins  on 
the    return   journey   to    the    heart 
where   it   enters  the  right  auricle 
again,  which  was  our  starting  place 
in  this  description  (Fig.  89). 

151.  Review    of     Circulation.  - 
The  blood  comes  from  the  tissues 
through  the  veins  and  enters  the 
right  auricle,  goes  through  the  tri- 
cuspid  valve  into  the  ventricle,  then 

through  the  semilunar  valve  it  enters  the  pulmonary  artery. 
Traversing  the  capillaries  of  the  lungs,  it  goes  by  the  pulmo- 


FlG.  89.  —  Diagram  illustrating 
the  Circulation. 

i,  right  auricle;  2,  left  auricle;  3, 
right  ventricle;  4,  left  ventricle  ; 
5,  vena  cava  superior  ;  6,  vena 
cava  inferior  ;  7,  pulmonary 
arteries;  8,  lungs;  9,  pulmonary 
veins;  10,  aorta  ;  n,  alimentary 
canal  ;  12,  liver ;  13,  hepatic 
artery  ;  14,  portal  vein  ;  15, 
hepatic  vein.  Follow  the  arrows 
and  see  whether  you  come 
around  to  the  starting  point  again. 


ELEMENTS   OF  PHYSIOLOGY 


FIG.  90.  —  Transverse  Section  of  Part  of  the  Wall 
of  an  Artery,  highly  magnified. 

,  epithelial  (endothelial)  layer,  or  inner  coat;  c,  muscular 
layer  or  middle  coat;  d,  outer  coat,  consisting  of  connective 
tissue. 


nary  veins,  to  the  left  auricle,  then  through  the  bicuspid,  or 

mitral,  valve  to  the  left  ventricle,  thence  into  the  aorta  by  the 

semilunar  valve,  thence  to  the  capillaries  of  the  system, 

thence  to  the  veins,  and  through  them  it  returns  to  the  heart, 

completing   the   circulation. 
152.  Structure  of 

Blood  Vessels.  —  In 

order  to  understand 

how    the     arteries, 

veins,   and    capilla- 
ries are  adapted  to 

their  work,  we  will 

study  their  anatomy. 

We  shall  find  three 

kinds  of  tissue  (Fig. 

90)   used    in    their 

construction,  —  epithelial  tissue  to  prevent  friction,  connect- 
ive tissue  to  give  both  strength 
and  elasticity,  and  muscular  tissue 
to  enable  the  vessels  to  change  in 
size. 

153.  The  epithelial  tissue  forms 
the  innermost  layer  of  the  vessels. 
The  endocardium  or  inner  lining 
of  the  heart  is  formed  of  this  mem- 
branous layer,  and  is  continued 
throughout  the  arteries,  capilla- 
ries, and  veins.  In  these  vessels 
it  is  called  the  endothelium.  The 
epithelial  cellsforming  this  smooth 

FIG.  9i.  -  Epithelial  Ceils  forming   layer  are  thm  and  flat,  and  serve  to 

the  Walls  of  Capillaries.  J    .    .  .     . 

Thenucleiandtheontlinesofthecells  dimmish    friction.         The    Walls    of 

may  be  seen.     The  forming  of  the  {he  capillaries,  the  Smallest  VCSSCls, 
thin  tubular  walls  of  the  capillaries  .  ...  . 

is  one  of  the  most  curious  among  the  COnSlSt     Simply    Of    thlS     epithelial 

ayerful  ^  accomplished    membrane  (Fig.  91 ).    In  the  small 


THE  CIRCULATION 


93 


arteries  a  layer  of  muscular  tissue  is  placed  outside  the 
endothelium.  Outside  of  this  muscular  tissue,  and  forming 
the  outer  surface  of  the  artery,  is  a  layer  of  connective 
tissue  containing  both  white  fibers  and  yellow  elastic  fibers 
(Fig.  90,  also  Fig.  32).  In  fact,  some  of  the  yellow  elastic 
fibers  (Fig.  32)  are  found  also  in  the  other  coats.  The 
muscular  and  connective  tissue  layers  become  still  thicker 
in  the  larger  arteries.  So  the  wall  of  an  artery  consists 
of  three  layers:  (i)  the  endothelium  ;  (2)  the  muscular  coat ; 
(3)  the  connective  tissue  coat  on  the  outside  (Figs.  90  and 
92).  The  arteries  are  therefore  very  firm  and  elastic,  and 
do  not  collapse  when  they  are  cut,  but  stand  open,  and  the 


-n 


A  V 

FlG.  92.  — An  Artery  and  Corresponding  Vein  cut  across. 

A,  artery  ;  V,  vein  ;  e.c,  endothelial  cells  ;   nt,  muscular  coat  ;  c ,  connective  tissue  ;  «,  nuclei 
of  endothelial  cells. 

flow  of  blood  through  them  is  unobstructed.  The  walls  of 
the  veins  consist  of  the  same  three  layers.  Their  walls  are 
not  so  thick  as  those  of  the  arteries,  for  the  muscular  and 
connective  tissue  layers  are  much  thinner  (Fig.  92).  When 
a  vein  is  cut  it  collapses,  that  is,  the  thin  walls  fall  together, 
and  the  bleeding  is  stopped  unless  the  vein  is  large. 

154.  The  Use  of  the  Three  Coats.  —  The  white  fibers  of 
the  connective  tissue  coat  (see  Fig.  90)  give  strength  and 
firmness  to  the  vessel,  and  the  yellow  elastic  fibers  give  elas- 
ticity. The  muscular,  or  middle,  coat  enables  the  arteries 
and  veins  to  change  in  size,  and  the  inner,  or  endothelial, 


94  ELEMENTS   OF  PHYSIOLOGY 

layer  gives  smoothness  and  prevents  friction.  Why  are 
these  three  properties  necessary  to  blood  vessels  ? 

155.  Why  the  Blood  Vessels  must  be  Elastic. —  The 
aorta  and  its  branches  are  full  of  blood  all  the  time. 
When  the  left  ventricle  with  its  great  muscular  walls  con- 
tracts, the  blood  cannot  move  forward  into  the  narrow 
arteries  and  capillaries  fast  enough  to  make  room  for  the 
new  supply  so  suddenly  sent  out  of  the  ventricle.  There- 
fore the  aorta  becomes  more  than  full.  If  a  cup  is  full,  it 
cannot  become  "  fuller"  ;  not  so  with  an  artery.  The  yellow 
elastic  fibers  of  its  connective  tissue  allow  it  to  expand  as 
a  rubber  hose  does  under  pressure.  The  first  part  of  the 
aorta  having  expanded  to  receive  the  incoming  blood,  the 
portion  of  the  aorta  just  ahead  of  the  expanded  portion  is 
less  tense,  or  tight,  so  the  stretched  elastic  fibers  contract 
and  force  blood  into  it,  expanding  it  in  turn.  Thus  a 
wave  of  expansion  travels  along  the  blood  vessel.  It  is 
called  the  pulse,  and  may  be  most  easily  felt  in  the  wrists 
and  neck.  The  distended  elastic  walls  exert  pressure  on 
the  blood  in  the  arteries,  and  this  presses  some  of  the  extra 
blood  out  of  them  into  the  capillaries.  As  much  blood  as 
is  being  pressed  on  into  the  capillaries  is  being  thrown  into 
the  aorta  by  the  beat  of  the  heart ;  so  that  during  life  a 
distension  is  always  kept  up,  and  the  blood  in  the  vessels 
is  always  under  pressure.  Although  the  arteries  may  get 
rid  of  the  additional  distension  following  each  heart  beat, 
there  is  a  normal  distension  that  always  remains.  It  has  ex- 
isted ever  since  life  began,  and  will  remain  until  the  heart 
ceases  to  beat.  The  pulse,  therefore,  is  only  an  additional 
distension  following  the  contraction  of  the  ventricle. 

You  should  not  think  that  the  muscular  layer  actively 
contracts  and  helps  to  send  along  the  pulse ;  for  the  pulse 
is  simply  the  passive  stretching  and  contracting  of  the 
elastic  tissue  ;  as  a  wave  travels  across  a  pond  when  a  stone 
is  dropped  into  the  water.  The  force  of  the  pulse  is 


THE    CIRCULATION  95 

furnished  by  the  heart.     What,  then,  is  the  purpose  of  the 
muscular  layer  in- the  arterial  wall? 

156.  Use  of  the  Muscular  Coat.  —  The  body  of  an  adult 
contains  about  five  quarts  of  blood.     We  have  learned  that 
the  blood  supplies  the  substances  needed  for  the  activity  of 
each  organ.     If  an  organ  is  working,  it  needs  more  blood 
than  usual,  which  is  supplied  by  the  other  organs  that  are 
at  rest ;  they  get  along  with  less  blood  for  the  time.     The 
muscular  coat  of  the  blood  vessels  makes  this  possible. 
This  coat  is  usually  in  a  condition  of  slight  contraction, 
but  the  nerves  controlling  the  muscular  coat  in  the  blood 
tubes  of  the  active  organs  may  cease  to  act,  thus  allowing 
the  muscular  coat  to  relax  and  the  blood  tubes  to  enlarge 
under  the  pressure  from  the  heart,  so  that  the  active  organs 
may  obtain  the  additional  supply  of  blood  needed.     While 
this  is  happening,  part  of  the  pressure  in  the  blood  tubes  of 
the  inactive  organs  is  relieved  and  they  become  smaller.     If 
cold  air  strikes  the  face,  the  nerves  stimulate  the  muscular 
coat  of  the  blood  tubes  in  the  face  to  contract  more  strongly 
than  usual,  and  the  face  turns  white.     This  driving  of  the 
warm  blood  from  the  face  saves  heat  to  the  body,  which 
would  be  lost  if  the  warm  blood  remained  in  the  skin. 
Thus  the  amount  of  blood  circulating  in  any  organ  is  regu- 
lated by  means  of  the  muscular  coat  of  the  blood  vessels 
and  of  the  action  of  the  nerves  upon  this  coat. 

157.  The  Use  of  the  Inner  Coat — We  learned  that  the 
inner  coat  of  the  heart  and  blood  vessels  is  made  of  epi- 
thelial tissue,  like  that  which  forms  the  outer  layer  of  the 
skin,  and  the  smooth  lining  of  the  mouth  and  other  organs. 
This  lining  membrane  is  very  smooth  and  thus  friction  is 
lessened.     The  friction,  however,  is  inconsiderable  in  the 
large  vessels ;  but  in  the  smaller  vessels  it  is  greater ;  and  in 
the  minute  capillaries  it  becomes  of  very  great  importance. 
We  see,  therefore,  why  it  is  necessary  to  have  this  smooth 
coat  in  the  capillaries,  although  the  muscular  and  connective 


96  ELEMENTS   OF  PHYSIOLOGY 

coats  are  not  prolonged  into  them.  It  should  be  stated 
here  that  although  the  extremely  minute  size  of  the  capil- 
lary tubes  increases  the  friction  and  the  pressure  which  the 
heart  must  expend  in  sending  the  blood  through  them,  yet 
their  resistance  to  the  blood  flow  is  lessened  by  their  great 
capacity.  The  united  capacity  of  the  capillaries  is  six  hun- 
dred times  that  of  the  blood  arteries  that  supply  them. 
In  the  capillaries  the  blood  flows  slowly  like  a  river  which 
flows  into  and  out  of  a  lake. 

158.  Rate  of  Flow  and  Differences  of  Pressure.  —  The 
velocity  of  flow  is  15  inches  per  second  in  the  aorta,  3^  of 
an  inch  per  second  in  the  capillaries,  and  about  7^  inches 
per  second  in  the  inferior  vena  cava.  When  an  artery  is 
cut,  the  blood  is  thrown  out  by  jerks  corresponding  to  the 
pulse,  and  flows  slowly  between  the  jerks  because  the 
arteries  are  kept  over-full  and  the  blood  is  pressed  out  by 
their  elastic  walls.  The  pressure  that  results  from  the 
arteries  being  always  over-full,  likewise  explains  why  the 
blood  flows  constantly  from  the  arteries  into  the  capillaries. 
Hence,  although  the  blood  is  thrown  into  the  aorta  at  in- 
tervals by  the  beat  of  the  heart,  it  flows  from  the  arteries 
to  the  capillaries  continuously,  being  only  quickened  in  its 
flow  by  each  beat.  In  the  capillaries,  owing  to  the  great 
friction  in  the  minute  passages,  there  is  strong  resistance 
to  the  flow  of  blood,  and  the  great  pressure  in  the  arteries 
is  necessary  to  send  the  blood  through  the  capillaries; 
a  great  deal  of  this  pressure  is  used  up  in  doing  so,  hence 
the  pressure  beyond  the  capillaries  (that  is  to  say,  in 
the  veins)  is  much  less  than  the  pressure  in  the  arteries. 
Enough  is  left  to  force  the  blood  part  of  the  way  through 
the  veins ;  but  it  is  not  sufficient  to  carry  the  blood  back  to 
the  .heart,  for  it  gives  out  entirely  before  the  heart  is 
reached.  We  shall  learn  later  how  the  contraction  of  the 
muscles  and  their  squeezing  effect  upon  the  veins  passing 
through  or  beneath  them,  aids  the  heart  to  move  the  blood  ; 


THE    CIRCULATION  97 

also  how  the  expansion  and  contraction  of  the  lungs  act  as 
a  great  pump  ;  and  how  these  aids,  together  with  changes  of 
posture,  enable  the  blood  to  reach  the  heart  again.  If 
one  stands  perfectly  still  for  some  time,  the  blood,  owing 
to  its  weight  and  the  lack  of  pressure  on  the  veins,  slowly 
congests  in  the  veins  in  the  lower  part  of  the  body,  and 
the  consequences  may  be  serious. 

159.  Hence  the  pressure  is  greatest  in  the  arteries,  less 
in  the  capillaries,  and  least  of  all  in  the  veins. 

160.  How  the   Amount   of  Blood  flowing   through  any 
Organ  may  be  modified.  —  We  learned  that  the  ability  to 
do  this  lies  in  the  muscular  or  middle  coat  of  the  vessels, 
and  that  the  muscular  coat  in  turn  is  controlled   by  the 
nerves.     This  very  important  power,  therefore,  is  intrusted 
to  the  two  master  tissues.     The  nerves  that  control  the 
sizes  of  the  blood  vessels  are  called  vasomotor  nerves  and 
are  of  two  kinds.     One  kind,  the  constrictor  nerves,  stimu- 
lates the  walls  of  the  blood  vessels  to  contract,  while  the 
other  kind  of  vasomotor  nerves,  called  the  dilator  nerves, 
neutralizes  or  inhibits  the  effect  of  the  constrictors,  and 
thus  allows  the  blood  tubes  to  enlarge.     The  regulation 
is  involuntary,  or  beyond  the  control  of  the  will;  for  in- 
stance, the  blood  vessels  of  the  brain  may  become  enlarged 
and  the  great  pressure  there  cause  a  headache,  but   the 
will  cannot  drive  it  away.     We  sit  before  a  fire,  and  the 
face  becomes  red  as  the  warmth  soothes  the  constrictor 
nerves  into  inactivity ;  or  the  constrictors  leading  to  the 
face  may  become  paralyzed  by  mental  confusion  and  we 
blush. 

161.  Why  must  the  Relative  Amount  of  Blood  in  the 
Different  Organs  continually  change  ?  —  The  necessity  for 
this  comes  from  the  fact  that  if  the  one  and  one  fourth 
gallons   of   blood  were   evenly    distributed,    none   of   the 
organs  would  be  capable  of  any  powerful  and  effective 
action.      A    person    weighing    157    pounds    has    only    12 


98  ELEMENTS   OF  PHYSIOLOGY 

pounds  of  blood,  for  the  blood  is  T^  of  the  total  weight  of 
the  body.  There  is  not  enough  blood  in  the  body  to  dis- 
tend all  of  the  blood  vessels  at  once.  The  skin  alone  with 
all  of  its  blood  vessels  distended  could  contain  two  thirds 
of  all  the  blood  in  the  body.  The  veins  have  twice  the 
capacity  of  the  arteries ;  they  could  contain  every  drop 
of  blood  in  the  body.  When  the  brain  works,  it  requires 
more  blood.  When  digestion  is  in  progress,  the  lining  of 
the  digestive  organs  blushes  a  rosy  red  and  the  digestive 
fluids  are  poured  out.  During  the  digestion  of  a  hearty 
meal,  one  will  not  do  his  best  thinking.  When  a  muscle 
is  used,  the  dilator  nerves  act,  the  blood  tubes  in  the 
muscle  become  enlarged,  and  its  supply  of  blood  increases 
to  serve  it  during  its.  action.  The  impulses  that  run 
along  the  vasomotor  nerves  arise  in  the  enlargement  at 
the  top  of  the  spinal  cord  called  the  spinal  bulb.  The 
part  of  the  spinal  bulb  that  in  this  way  regulates  the 
caliber  of  the  arteries  is  called  the  vasomotor  center.  It 
is  constantly  sending  impulses  along  the  constrictor  fibers 
so  as  to  keep  the  muscles  of  the  arteries  slightly  con- 
tracted. The  vasomotor  center  thus  keeps  a  rein  upon 
the  arteries,  holding  them  in  a  condition  of  tone,  as  this 
slight  contraction  is  called.  Sudden  paleness,  due  to  fear, 
is  brought  about  by  extra  strong  impulses  from  the  vaso- 
motor center,  causing  the  muscular  walls  of  the  small  arter- 
ies of  the  face  to  grip  the  vessels  tight  and  drive  the  blood 
from  the  face.  Alcohol  destroys  the  tone  of  the  blood 
tubes.  From  temporary  drinking  the  face  becomes  red  ; 
from  habitual  drinking  the  "  rum  blossom,"  the  purple 
swollen  blood  tubes  in  the  nose,  results. 

162.  How  the  Flow  of  Blood  through  the  Whole  Body 
is  regulated.  —  The  amount  of  blood  passing  through  one 
organ  may  be  increased  by  the  vasomotor  nerves,  but  it 
is  only  because  the  amount  going  through  the  enlarged 
vessels  of  that  organ  has  been  withdrawn  from  other 


THE  CIRCULATION  99 

organs  whose  blood  tubes,  not  being  enlarged  just  then, 
afford  greater  resistance  to  the  passage  of  the  blood  than 
the  dilated  vessels  afford.  But  can  the  total  amount  of 
blood  reaching,  in  a  given  time,  not  a  single  organ  only, 
but  all  the  organs  in  the  body,  be  increased  ?  Yes,  for 
if  the  one  and  one  fourth  gallons  of  blood  flow  faster  all 
over  the  body,  more  fresh  blood  will  reach  each  organ. 
This  is  accomplished  by  faster  or  stronger  beating  of 
the  heart.  During  rapid  general  exercise,  as  running, 
when  the  demands  of  the  body  are  increased,  the  heart 
beats  faster,  as  you  have  doubtless  observed.  When  the 
body  in  general  is  at  rest,  as  during  sleep,  the  heart 
beats  more  slowly.  Thus  the  general  blood  supply  is 
regulated.  But  how  is  the  heart  itself  regulated  ?  For 
these  facts  show  two  things :  first,  that  we  cannot  directly 
control  it  by  the  will;  and  second,  that  there  is  some- 
thing in  the  body  that  does  control  the  heart,  and  perhaps 
our  wills  may  influence  the  beating  of  the  heart  indirectly. 
The  heart,  like  the  blood  vessels  and  the  muscles  in  gen- 
eral, is  supplied  with  nerves ;  but  there  is  this  difference, 
namely,  that  the  heart  can  go  on  beating  without  receiv- 
ing impulses  along  its  nerves.  The  heart  of  a  frog,  after 
being  cut  out  of  the  body,  will  go  on  beating  for  several 
hours  if  it  is  kept  moist;  if  it  is  cut  into  several  pieces, 
the  pieces  will  go  on  beating.  It  is  the  property  of  the 
heart  muscle  to  contract,  and  it  will  do  so  as  long  as  its 
protoplasm  is  alive. 

163.  The  nerves  going  to  the  heart  do  indeed  carry 
impulses  to  the  heart,  but  this  is  to  regulate  the  beat  of  the 
heart  and  not  to  originate  it.  A  nerve  called  the  vagus 
nerve,  extending  from  the  spinal  bulb  to  several  organs, 
goes  to  the  heart ;  and  gentle  impulses  which  are  almost 
always  passing  down  the  vagus  nerve  from  the  spinal  bulb, 
restrain  the  heart  from  too  great  activity,  and  are  the 
chief  means  of  regulating  the  strength  and  frequency  of 


100  ELEMENTS   OF  PHYSIOLOGY 

its  beats.  When  an  animal  requires  a  greater  supply  of 
blood,  as  in  running,  these  impulses  for  a  time  cease,  and 
the  heart  beat  is  quicker  and  stronger  (Fig.  202). 

164.  There  are  other  nerves,  called  sympathetic  nerves, 
connected  with  the  spinal  cord  below  the  point  at  which 
the  vagus  branches,  that  bring  impulses  to  the  heart  which 
are  opposite  in  effect  to  those  brought  by  the  vagus. 
These  impulses  also  start  in  the  spinal  bulb ;  they  cause  a 
quickening  and  strengthening  of  the  beats  (Fig.  200). 
Do  the  vagus  nerve  fibers  or  the  sympathetic  nerve  fibers 
resemble  the  whip  which  a  driver  uses  in  driving  a  horse  ? 
Which  kind  corresponds  to  the  reins  ?  Thus  the  need  of 
the  body  for  a  greater  or  less  active  blood  supply  is  regu- 
lated by  controlling  the  rate  and  strength  of  the  heart 
beats.  If  the  nerves  are  all  in  order,  the  heart  beats  more 
slowly  when  the  tissues  of  the  body  need  little  blood,  and 
more  rapidly  when  the  tissues  need  more  food  or  more 
oxygen.  But  quickening  of  the  heart  beat  cannot  send 
more  blood  through  one  organ  without  sending  more 
blood  through  all  the  organs,  hence  it  is  not  so  delicate  a 
means  of  regulating  the  blood  supply  as  the  vasomotor 
system. 


?r^&- 


COLEMAN'S   ANATOMICAL    MANIKIN 


JtfUBHBBI 


100 


PLATE     II 


PLATE     III. 

Viscera  (front  view).     For  rear 
view,  see  next  plate. 


t^w- 


100 


PLATE      IV. 

Viscera  (rear  view).  Student  will  find 
ducts  from  the  liver  and  pancreas  enter- 
ing duodenum  together;  also,  mesen- 
teric  artery  leading  to  intestines  and 
portal  vein  leading  from  them  to  liver. 


PLATE     V. 


I 


I'm 


-.,    - ,. 


|lp 
Itiixi 


PLATE     VI. 


PLATE     VII. 


PLATE     VIM 


The  pupil  will  trace  the  circulation  of  the  blood  from  the  body  through  the  right  side  of  the 
heart  to  the  lungs;  and  from  the  lungs  through  the  left  side  of  the  heart  to  the  body;  also 
trace  the  portal  circulation,  from  the  digestive  organs  through  the  liver  to  the  heart. 


CHAPTER  VIII 
THE  CIRCULATION   (continued) 

165.  How  the  Heart  is  aided  in  its  Work. —The  heart 
seems  to  be  constantly  at  work,  but  such  is  not  the  case. 
As  a  matter  of  fact,  the  heart  occupies  nearly  as  much 
time  in  resting  as  in  working.     It  works  for  about  half  a 
second   and  rests  for  about  half  a  second.      Yet  it  does 
work  in  a  day  equivalent  to  raising  a  ton  of  coal  nearly 
two  hundred  feet. 

166.  Increase  the  circulation  in  the  arm  by  exercising  it 
for  a  few  minutes.     The  veins  in  the  front  of  the  wrist  will 
then  be  plainly  visible.     The  skin  and  walls  of  the  veins 
make  the  blood   in  the  veins  appear  blue,  but  it  is  dark 
purplish  red.     (Did  you  ever  see  "blue"  blood?)     Place 
the  tip  of  the  forefinger  on  one  of  the  large  veins ;  with  the 
middle  finger  then  stroke  the  vein  toward  the  hand  so  as 
to  push  the  blood  from  a  portion  of  it,  keeping  the  two 
fingers  in  place.      The  vein  remains  empty  between  the 
fingers.     Lift  the  finger  nearer  the  heart  and  no  blood 
enters  the   vein ;    there   is  a  valve  above  which  holds  it 
back.     Lift  the  other  finger,  and  the  vein  fills  instantly. 
Stroke  a  vein  toward  the  hand,  and  see  the  blood  cause 
the  veins  to  swell  up  into  little  knots  where  the  valves  are. 
(Experiments  upon  veins  are  plainest  with  adults  whose 
veins  are  large.)    The  veins  have  valves  placed  frequently 
along  their  course.      The  valves  are  pockets  made  by  a 
fold  in  the  inner  coat  of  the  wall  of  the  vein  (Fig.  93). 
When   you  place  your   hand   in  your   pocket,    the   latter 

101 


IO2  ELEMENTS   OF  PHYSIOLOGY 

swells  out;  but  if  you  rub  your  hand  on  the  outside  of 
the  pocket  from  the  bottom  toward  the  top,  it  flattens 
down.  So  with  the  action  of  the  blood  upon  the  valves 
in  the  veins  (Figs.  94,  95).  They  all  open  toward  the 
heart. 

167.    Suppose   a   muscle    hardens   as   it   contracts   and 
presses  upon  a  vein  which  goes  through  the  muscle;  the 
blood  is  pressed  out  of  the  vein.     The 
>  blood  cannot  go  toward  the  capillaries, 

i-     *^  -*H  for  the  valves  fill  and  close  when  it  starts 

_      that  way  ;  so  it  is  all  pressed  out  toward 
the  heart.      When  the  muscle  relaxes, 
the  blood  that  has  been  pressed  for- 
FIG.  93  -Diagram  of  the  ward  cannot    come    back    because   of 

Valves  01  Veins. 

H,  heart  side  ;  c,  capillary  the  valves,  but  the  valves  nearer  the 


filled.  When  the  muscle  contracts 
again,  the  same  effect  on  the  blood  movement  is  re- 
peated. We  see,  therefore,  that  every  contracting  muscle 
converts  into  a  pump  the  vein  running  through  it,  and 
when  a  person  works  or  exercises,  many  little  pumps 
are  working  all  over  the  body,  aiding  the  heart  in  its 
function. 

168.  This   aid   makes   the   blood    flow    faster   and    re- 
lieves the  heart  of  part  of  its  work,  so  that  it  beats  faster, 
just  as   a  horse  might  trot  faster  if    half  the   load  were 
removed.      All  of   the   body   gets  fresher   blood  than  it 
got  when  the  muscles   were    still   and   the  blood   flowed 
more  slowly.     This  help   comes  during  active  work,  just 
when  the  body  is  demanding  more  blood  and  the  heart 
needs  help. 

169.  Suppose  a  person  engages  in  vigorous  muscular  ex- 
ertion just  after  eating.      The  stomach  and  the  muscles 
both  demand  an  increased  supply  of  blood.     The  muscles 
will  get  it  because  the  valves  in  the  veins  will  increase  the 


THE   CIRCULATION 


103 


flow  through  the  muscles,  and  the  muscles  are  so  extensive 
and  use  so  much  blood  that  the  digestion  may  surfer  be- 
cause of  the  vigorous  exercise. 

170.  Massage.  —  So  effective  and  necessary  is  exercise  in 
aiding  the  circulation,  that  some  people  employ  others  who 
are  skilled  in  the  art  called  massage,  to  come  regularly  and 
squeeze  and  knead  every  muscle  like  dough.     Thus  fresh 
blood  is  brought  and  the  removal  of  waste  material  from 
the  tissues  is  aided.      If   a  boy  has  so-called   "growing 
pains  "  which  may  come  from  over-fatigue,  or  which  may 
be  a  light  form  of  rheumatism 

from  exposure  to  wet  and  cold, 
his  pains  can  be  relieved  by 
thoroughly  rubbing  the  aching 
part. 

171.  The    arteries    lie    deep 
under    the    muscles    near    the 
bones,  and  are  likewise  pressed 
upon    by    muscles,     but    their 
walls  are  much  stiff er  than  the 
walls   of    the    veins.      In 
many    of    them    in    passing 
through  the  muscles  have  tough, 

fibrous  sheaths.  It  is  well  that  the  arteries  are  not 
so  much  affected  by  exercise,  for  if  they  were  squeezed 
by  the  contracting  muscles,  the  blood  would  be  pressed 
backward  as  well  as  forward  since  they  are  destitute 
of  valves,  and  this  would  not  be  favorable  to  the 
circulation. 

172.  The   Lungs   aid   the   Heart   to  circulate  the  blood 
since  when  they  expand  and  the  air  rushes  into  them,  the 
blood  as  well  is  drawn  toward  the  cavity  of  the  chest, 
and  when  they  contract,  the   blood  tends   to  leave  this 
^egion. 

173.  Does  the   elasticity   of   the   arterial   wall   furnish 


FIG.  94.  — Vein 
fact,       laid  open  to 
show  Two 
Valves. 


FIG.  95.  — Valve 
in  Vein  dis- 
tended  with 
Blood. 


IO4 


ELEMENTS   OF  PHYSIOLOGY 


any  force  to  aid  the  heart?  No.  When  the  arteries 
contract  as  the  pulse  passes,  it  is  the  force  of  the  heart 
that  is  doing  it.  When  you  open  a  door  or  gate  that 
is  closed  by  an  elastic  spring,  it  is  the  force  furnished 
by  you  to  the  spring  that  shuts  the  door  after  you 
release  your  hold. 


THE  LYMPHATIC  SYSTEM 

174.  How  the  Nourishment  gets  from  the  Blood  into  the 
Tissues.  —  We  left  the  food  and  oxygen  in  the  capillaries. 
How  does  it  get  out  of  them  into  the  tissues  ?     We  found 
that  the  blood  flows  very  slowly  in  the  capillaries  (g1^  of  an 

inch  per  second),  and  that  the 
capillary  walls  are  very  thin, 
being  made  of  only  the  inner 
of  the  three  coats  that  make 
the  veins  and  arteries.  Here, 
then,  are  two  favorable  con- 
ditions for  giving  up  the  nu- 
trition (Fig.  96).  We  learned 
that  the  albumin,  sugar,  and 
fats  were  dissolved  in  the 
plasma,  or  liquid  portion  of 
the  blood.  The  plasma 
passes  through  the  thin  cap- 

Capillaries    connecting    a    small    artery,  a,   iHary       walls,        Carrying       the 
with  a  small  vein,  b.  J  J 

food  with  it.     When  it  gets 

outside  the  capillaries,  it  is  next  to  the  walls  of  the 
cells  that  make  up  the  tissues.  These  spaces  are  called 
lymph  spaces.  Thus  the  lymph  bathes  the  cells  in  the 
nutritious  fluid,  and  the  hungry  cells  absorb  what  they 
need. 

175.  The  red  corpuscles  bearing  the  oxygen  cannot  get 
through  the  capillary  walls.      Oxygen  is  a  gas,  however, 


FIG.  96. 


THE    CIRCULATION 


105 


and  the  walls  of  the  capillaries  are  so  thin  that  they  offer 
no  hindrance  to  the  passage  of  the  oxygen  into  the  cells  in 
the  tissues.  Carbon  dioxid,  which  is  one  of  the  products 
of  the  combination  of  oxygen  with  the  food  material  in 
the  tissues,  is  also  a  gas,  and  it  passes  back  through 
the  capillary  walls  into  the  blood,  which  takes  it  back 
to  the  heart,  and  thence  to  the  lungs  to  be  sent  out  of 
the  body. 

176.  Why  cannot  the  capillaries  themselves  carry  the 
food  into  the  tissues  ?     Because  they  are  tubes,  and  as  long 
as  the  food  is  in  the  blood  it 

cannot  reach  the  cells ;  the 
capillary  walls  prevent.  The 
lymph  spaces  and  the  lym- 
phatics act  as  middlemen  be- 
tween the  blood  and  the  cells 
(Fig.  97). 

177.  Necessity  for  the  Lym-     FIG.  97.— Diagram  to  show  Function 

phatic  System. — If  the  plasma 
kept  coming  into  the  tissues 
without  any  way  of  getting  back  into  the  blood  vessels, 
the  blood  would  soon  be  lacking  in  plasma  and  the  tissues 
would  be  oppressed  with  it.  We  see,  then,  the  absolute 
necessity  for  some  provision  to  get  this  liquid  bark  into 
the  blood  vessels,  from  which  it  is  constantly  overflowing, 
This  is  done  by  a  system  of  tubes  called  the  lymphatics 
(Fig.  98). 

178.  What  is   lymph  ?      The  blood    plasma  is    called 
lymph  after  it  gets  out  of  the  capillaries.     But  it  soon  be- 
comes changed  by  the  addition  of  substances  thrown  out 
by  the  cells,  and  by  giving  up  to  the  cells  the  digested 
food  brought  by  the  blood.     We  should  have  said  also  that 
the  white  blood  corpuscles  may  pass  out  into  the  lymph, 
especially  if  there  is  some  condition  in  the  tissues  that  they 
can  correct  (Fig.  82). 


of  Lymph. 
A,  tissue  cells  ;  C,  capillary;  L,  lymphatic. 


io6 


ELEMENTS   OF  PHYSIOLOGY 


179.  We  may  say,  then,  that  lymph  is  nearly  the  same 
as  the  blood  without  the  red  corpuscles.     Did  you  ever 
see  any  lymph  ?     Certainly  you  have  seen  it,  many  times. 
Whenever  there  is  a  blister  in  the  skin  from  friction,  or 
from  a  burn,  the  lymph  collects.      Sometimes  when  the 
skin  is  grazed,  but  no  blood  vessel  touched,  the  lymph 
may  exude. 

180.  The  Origin  and  Course  of  the  Lymphatics.— Unlike 
the  blood  vessels,  the  lymphatics,  or  the  tubes  which  carry 

the  lymph,  have  a  beginning.  The  blood 
vessels  do  not  begin,  but  make  a  never- 
ending  circle.  The  lymphatics  begin  in 
open  ends  between  the  capillaries  and  the 
cells,  or  among  the  cells  themselves  (Fig.  97). 
It  will  be  interesting  to  learn  how  they 
lead  the  lymph  back  to  the  circulation,  and 
what  makes  it  flow,  for  surely  there  is  no 
heart  for  the  lymph  as  there  is  for  the 
blood.  When  the  lymph  once  enters  the 
open  end  of  the  lymphatic,  it  does  not 
return  to  the  blood,  but  continues  to  move 
slowly  or  at  intervals  through  the  lymphatics 
on  its  return  to  the  blood  system  (Fig.  98). 
Small  lymphatics  come  together  and  form 
larger  ones.  They  continue  to  unite  and 
form  larger  ones,  until  finally  the  lymphatics 
from  nearly  the  entire  body  unite  into  one 
FIG.  98.  — The  iarpre  tube,  which  passes  up  through  the 

larger    Lympha-  * 

tics  of  the  Front     abdomen   and  thorax,  and   pours  the  lymph 
of  the  Right  Arm.     into  t^Q   venous   system   beneath  the.  collar 

g;  lymphatic  glands.       .  .  „,,   .        ..  .         .. 

bone   near   the   neck.      This  largest   of    all 
lymphatics  is  called  the  thoracic  duct. 

181.  The  Thoracic  Duct  is  about  the  size  of  a  goose  quill, 
and  empties  into  the  venous  system  just  where  the  large 
vein  from  the  left  side  of  the  head  (the  left  jugular  vein) 


THE   CIRCULATION 


107 


joins  the  large  vein  from  the  left  arm  (left  subclavian  vein) 

(Fig.  99).    We  said  the  lymphatics  from  nearly  all  over  the 

body  form  the  thoracic  duct; 

but  the  lymphatics  from  the 

right  arm  and  right  side  of  the 

trunk  and  head  form  what  is 

called  the  right  lymphatic  duct, 

which  empties  into  the  right 

subclavian  vein  just  where  the 

right  jugular  vein  joins   the 

latter  (see  Plates). 

182.  What  makes  the 
Lymph  flow  ?  —  Did  we  not 
learn  that  something  besides 
the  heart  makes  the  blood 
flow  ?  It  is  the  contraction 
of  the  muscles  and  their  con- 
sequent pressure  upon  the 
veins.  The  valves  in  the 
veins  make  this  pressure 
effective  by  allowing  the 
blood  to  be  forced  in  only 
one  direction.  It  is  likewise 
found  that  the  lymphatics 
have  valves,  and  that  they  are 
more  abundant  than  those  of 
the  veins.  Whenever  the 
muscles  contract,  the  lymph 
is  forced  along,  and  the  valves 
provide  that  no  progress  made 
shall"  be  lost  by  any  backward 
movement.  Every  pressure 
leaves  a  part  of  the  lymphatic 
empty  and  ready  to  fill  from  behind  (Fig.  100).  Also,  if 
the  body  is  pressed  upon  or  shaken,  as  when  riding  a  trot- 


FlG.  99.  —  The  Thoracic  Duct. 

i,  part  of  ribs  ;  a,  receptaculum  chyli ;  b, 
trunk  of  thoracic  duct,  opening  at  c  into 
junction  of  left  jugular  (/)  and  left  sub- 
clavian ( g")  veins.  The  connection  of  these 
veins  with  the  superior  vena  cava(A)  has 
been  cut  across  to  show  the  thoracic  duct 
behind  it  ;  d,  lymphatic  glands  in  the  lum- 
bar regions. 


io8 


ELEMENTS   OF  PHYSIOLOGY 


ting  horse,  or  in  a  jolting  vehicle,  the  lymph  is  moved  be- 
yond the  valves  at  every  jolt,  and  its  circulation  aided. 

183,  The'  secret  of  the  powerful  effect  of  muscular  work 
upon  the  health  lies  chiefly  in  the  great  aid  that  it  gives 
the  lymphatic  and  venous  circulations.  The 
importance  of  an  active  lymphatic  circulation 
is  seen  when  we  remember  that  the  blood 
does  not  make  its  exchange  directly  with  the 
cells  of  the  tissues,  but  with  the  lymph,  and 
the  lymph  makes  the  exchanges  with  the 
tissue  cells. 

184.  The  Lymphatic  Glands.  —  Along  the 
course  of  the  lymphatics,  numerous  enlarge- 
ments occur  called  lymph  nodes  or  lymph 
glands  (Fig.  101).  They 
consist  of  a  connective 
tissue  framework,  the 
meshes  of  which  are 
crowded  with  lymph  cells. 
The  lymph  in  its  course 
must  filter  through  these 
clusters  of  cells,  and,  in 
doing  so,  is  purified;  for 
the  node  cells  take  up 
impurities  in  the  lymph, 
and  work  over  and  change 
The  cells  in  these  nodes 
multiply,  and  some  of  them  are  taken  up 
by  the  lymph  and  carried  into  the  blood 
to  become  those  remarkable  little  bodies, 
the  white  blood  corpuscles.  It  is  a  curi- 
ous fact  that  the  older  white  corpuscles 
are  broken  up  in  the  lymph  nodes,  and  their  remains  are 
absorbed  by  the  newly  formed  white  corpuscles,  just  as  the 
latter  absorb  germs  and  other  foreign  particles  that  may 


FIG.  loo.  — A  Full 
Lymphatic  with 
its  Valves  dis- 
tended. 

their  nature. 


FIG.    101.  —  Lymphatic 
Gland. 

Showing  valved  lymphatics 
entering  and  leaving  it. 


THE    CIRCULATION  IOQ 

enter  the  blood.  The  lymphatics  penetrate  and  help  in 
the  nourishment  of  every  tissue,  even  in  that  of  the  bony 
tissue  (Fig.  102). 

185.  The  Spleen.  — This  organ  resembles  the  lymph  nodes. 
It  is  purplish  red,  about  five  inches  in  length,  and  is  situ- 
ated just  inside  of  the  lower 

ribs  on  the  left  side  of  the 
abdomen.  White  corpuscles 
are  formed  in  it  as  well  as  in 
the  smaller  lymph  nodes.  In 
it  also  the  red  corpuscles  that 
have  finished  their  service 
in  the  blood  are  probably 
broken  up  and  destroyed. 

HYGIENE   OF  THE   CIRCU-         FIG.    102.  — Section    of    a    Haversian 
T  ATTrkxr  Canal,  showing  its  Contents,  highly 

magnified. 

186.  Have  VOU  learned  Vet    a>  sma11  arterial  capillary  vessel;  v,  large 

J  venous  capillary;  «,  pale  nerve  fibers  cut 

the  CUrioUS  fact  that  all  01  the  across  ;  /,  cleftlike  lymphatic  vessel;  one 

,..  ,,          r     ,••         «      j        i«  °f  the  cells  forming   its    wall   communi- 

llVing     CellS    01     the     DOdy    live  cates  by  fine  branches  with  the  branches 

under  water,  j  ust  as  the  ameba  of  a  bone  corpuscle- 
does  ?  The  lymph  and  the  blood  are  chiefly  water  and  the 
cells  are  all  bathed  continually  in  one  or  the  other.  The 
blood  bathes  the  cells  in  the  walls  of  its  vessels,  and  the 
lymph,  or  the  blood  without  the  red  corpuscles,  is  found 
filling  the  interstices  or  spaces  between  the  cells,  like  water 
in  a  sponge.  From  the  spaces,  as  we  learned,  it  is  taken 
by  the  lymphatics  in  order  to  make  room  for  fresh  lymph, 
free  from  waste  material  and  bringing  fresh  nourishment. 
The  only  exception  to  the  rule  that  the  cells  live  a 
watery  existence,  is  found  on  the  surface  of  the  body ;  the 
cells  of  the  outer  skin,  hair,  and  nails,  however,  may  be 
called  dying  cells,  for  they  are  not  alive  in  the  same  sense 
that  the  other  cells  are :  they  do  not  contain  nuclei  and 
cannot  repair  themselves  or  grow. 


1 1 0  ELEMENTS   OF  PHYSIOL OGY 

187.  The  supreme,  the  transcendent  importance  to  the 
health  of  the  tissues,  of  pure  blood  and  good  circulation,  now 
becomes  apparent.     All  that  the  cells  need,  in  order  to  be 
sound   and   vigorous,  is   to    have  good    food  and  oxygen 
brought  within  their  reach,  and  to  have  the  waste  material, 
or  products  of  combustion,  removed  ;  the  circulation  meets 
these  needs. 

188.  When  unsoundness  occurs  in  any  part  of  the  body, 
there   is   a   strong   probability  that  the  circulation  there 
is  defective.     The  hair  is  lost  by  cutting  off  the  circulation 
from  the  scalp.     The  eyes  may  become  inflamed,  or  the  lids 
diseased,  because  of   obstructing  in  the  neck  the  return 
of  the  blood  from  the  head;    improper  neck  clothing  or 
stiffened  muscles    may  cause    this   obstruction.      A  corn 
grows  on  the  toe  because  of  the  interruption  of  the  circula- 
tion  there,    resulting  from   intermittent   pressure   of   the 
upper  leather  of   a  tight   shoe  upon  the   toe  as  the  foot 
lengthens   and  shortens  at  every  step.     Indigestion  may 
result  if  vigorous  mental  or  physical  activity,  just  after 
eating,  draws  the  blood  away  and  prevents  the  secretion 
of  the  digestive  fluids.     Gout  may  occur  from  the  deposit 
of  waste  materials  in  the  spaces  around  the  joints  where 
the  pressure  from  the   circulation  is    least.     Colds  occur 
when  the  blood  vessels  in  the  walls  of  the  air  passages  be- 
come congested  or  swollen  with  blood,  and  the  vessels  lose 
their  tone  so  that  they  cannot  contract  and  keep  the  blood 
moving  onward. 

189.  Pure  Blood  is  just  as  necessary  as   free  and  unim- 
peded circulation.     We  shall  learn  later  how  the  digestive 
organs  serve  to  furnish  the  nutrition,  how  the  lungs  furnish 
the  oxygen,  and  how  the  skin,  kidneys,  and  lungs  remove 
from  the  blood  the  impurities  and  waste  materials. 

190.  Taking  Cold.  —  Sudden  or  prolonged  exposure  to 
cold  while  the  muscles  are  inactive,  so  stimulates  the  sur- 
face blood  vessels  through  the  vasomotor  nerves  that  they 


THE   CIRCULATION  III 

become  tightly  contracted  and  send  the  blood  to  the  in- 
terior of  the  body.  It  accumulates  there  and  may  cause 
such  congestion  of  the  mucous  membrane  of  the  nose, 
throat,  windpipe,  or  lungs,  that  inflammation  ensues.  A 
cold  is  an  inflammation  of  the  mucous  membrane  of  part 
of  the  air  passages.  Rapid  cooling  off  from  a  heated 
condition,  especially  if  one  is  in  a  profuse  perspiration, 
may  cause  the  same  results ;  or,  exposure  to  moderate  but 
continuous  cold  without  exercising  may  bring  on  a  cold. 
Sitting  on  the  damp  ground,  sitting  with  damp  feet,  sitting 
for  a  long  time  in  a  cool  draught,  or  going  thinly  clad  in  cool 
weather,  may  cause  a  cold;  only  foolish  persons  think 
they  are  so  hardened  as  to  withstand  such  risks  without 
injury.  Persons  who  pay  attention  to  their  feelings  and 
instincts  can  detect  the  beginning  of  any  such  derange- 
ment of  the  circulation,  and  prevent  trouble  by  timely 
prudence. 

191.  A  person  may  be  in  the  habit  of  coddling  himself 
by  living  in  overheated  rooms,  or  by  wearing  too  warm 
clothing  and  by  constant  use  of  mufflers  on  going  out ;  his 
surface  nerves  thus  become  so  delicate  ^nd  the  blood  vessels 
of  the  surface  so  relaxed,  as  to  insure  taking  cold  on  every 
accidental  or  unavoidable  exposure.     A  better  plan  is  to 
keep  the  house  cool,  the  thermometer  standing  at  65°  or 
70°,  sleep  with  open  windows,  take  cool  baths,  and  keep 
warm  when  out  of  doors  by  walking  or  exercising  briskly. 
Thus  the  blood  vessels  are  toned  up,  the  circulation  is  made 
vigorous  and  steady,  and  the  person  is  better  fitted  to  with- 
stand the  ordinary  conditions  of  life  without  disease  con- 
tinually recurring  owing  to  deranged  or  weak  circulation. 
Any  process  of  "  hardening  to  cold  "  that  is  not  accom- 
panied by  vigorous  exercise,  is  a  risk  to  the  health. 

192.  The  reciprocal  action  of  the  blood  vessels  of  the  skin 
and  the  internal  organs  is  sometimes  illustrated  when  a 
person  drinks  freely  of  cold  water.     There  is  a  sudden 


112  ELEMENTS   OF  PHYSIOLOGY 

breaking  out  of  perspiration.  Why  is  this  ?  Certainly  the 
water  does  not  reach  the  skin  so  quickly.  The  cold  in 
the  interior  stimulates  the  internal  vessels  to  contraction 
and  the  blood  is  diverted  to  the  unstimulated  vessels  of  the 
skin,  surrounding  the  sweat  glands. 

193.  Effects   of  Unusual   Exercise.  —  If    a   person    has 
sedentary  habits   and  has   neglected   active   exercise   for 
some  time,  the  heart,  as  well  as  the  other  muscles,  becomes 
weak.     If  such  a  person  hurries  to  catch  a  train,  or  takes 
very  rapid  and  trying  exercise  of  any  kind,  he  may  bring 
on  an  unpleasant  palpitation  of  the  heart,  which  is  a  warn- 
ing to  desist  at  once.     Violent  exercise  should  not  be  taken 
until  one  has  gradually  led  up  to  it. 

194.  Sleep  and  the  Blood.  —  A  person  who  loses  much 
sleep  becomes  pale ;  the  paleness  is  evidence  of  a  diminu- 
tion in  the  number  of  red  corpuscles.     It  is  during  sleep 
that  the  corpuscles  that  have  been  worn  out  during  the  day 
are  replaced,  but  loss  of  sleep  causes  a  greater  loss  to  the 
blood  than  usual,  with  less  than  the  usual  opportunity  for 
repair. 

195.  Mental  Influences.  —  Rage  excites  and  strains  the 
heart.     The  unexpected  receipt  of  joyful  news  sometimes 
so  acts  upon  the  heart  through  the  emotions  as  to  cause 
death.     Thinking  intently  of  an  organ  may  cause  an  in- 
crease of  the  circulation  in  it. 

196.  Clothing.  —  The  blood  cannot  circulate  with  perfect 
freedom  unless  the  entire  body  is  so  loosely  clothed  that 
there  is  no  pressure  upon  any  of   the   blood  vessels,  no 
interference  with  the  lungs  as  they  expand,  no  pressure 
upon   the   stomach,  liver,   and   intestines.     Many   of   the 
largest  veins,  particularly  those  of  the  arms  and  legs,  lie 
so   near   the  surface  that  any  tightness   of   the   clothing 
is   certain  to  diminish  the  flow   of  blood  through  them. 
Sleeve  supporters  and  garters,  if  used  at  all,  should  be 
of   weak   elastic   with   adjustable  buckle,  and  no  tighter 


THE   CIRCULATION  113 

than  is  absolutely  necessary.     It  is  especially  necessary  to 
keep  the  extremities  warmly  clad  and  dry. 

197.  Effects  of  Alcohol  upon  the  White  Corpuscles.  —  Dr. 
Woodhead,  of  the  University  of  Cambridge,  says  that  the 
white  corpuscles  are  injured  by  alcohol  in  the  blood,  and 
that  they  lose  to  some  extent  their  activity  in  attacking 
poisons  and  germs  of  disease.     This  gives  an  explanation 
of  the   susceptibility  of   drinking  men  to  germ  diseases. 
Persons  accustomed  to  use  alcohol  are  usually  the  first  vic- 
tims of  cholera  and  of  yellow  fever ;  while  some  abstainers, 
under  constant  exposure,  remain  untouched.     The  white 
corpuscles  repair  cuts  and  broken  bones  ;  hence  intemperate 
persons  do  not  recover  from  accidents  and  surgical  opera- 
tions as  quickly  as  do  total  abstainers. 

198.  Effect  of  Alcohol  upon  the  Red   Corpuscles.  —  The 
red  corpuscles  carry  the  oxygen.     When  alcohol  is  freely 
taken,  the  red  corpuscles  are  injured  so  that  the  blood  loses 
in  part  its  power  to  carry  oxygen.     The  injury  is  to  the 
red  coloring  matter  of  the  corpuscles. 

199.  How  the  Heart  may  beat  faster  without  expending 
More  Strength.  —  Prof.  Destree  says  that  increased  action 
of   the  heart  only  appears  to  be  a  stimulation,  and  that 
alcohol  is  a  narcotic  (from  the  Greek  narkonn,  to  benumb). 
Its  effect  on  the  heart  is  thus  explained  :    The  benumbing 
effect  of  the  alcohol  upon  the  constrictor  nerves  (§  160)  of 
the  arterial  walls,  paralyzes  these  walls,  allowing  them  and 
the  capillaries  to  dilate,  thus  lessening  the  friction  and  re- 
ducing the  blood  pressure  in  the  vessels.     The  heart  keeps 
on  exerting  the  same  force  from  habit ;  and  since  it  is  pump- 
ing against  less  resistance,  the  same  exertions  of  the  heart 
suffice  to  make  it  pump  faster  for  a  time  and  send  the  blood 
over  the  body  faster.     When  a  dam  is  broken  down,  the 
water  flows  faster  for  a  time ;    the  force  of  the  flow,  how- 
ever, is  not  supplied  by  the  weakness  of  the  dam  in  break- 
ing down. 

i 


1 1 4  ELEMENTS  OF  PH YSIOL OGY 

200.  But  Alcohol  affects  the  Heart  itself.  —  "  The  valves, 
which  consist  of  folds  of  membrane,  lose  their  suppleness 
and  become  diseased  and  weakened.     The  muscular  fiber 
of  the  heart  is  replaced  by  fatty  cells,  so  that  the  power  of 
contraction  is  greatly  reduced.     These  derangements  are 
likely  to  cause  death  from  sudden  failure  of  the  heart  itself, 
or  from  rupture  of  the  weakened  blood  vessels,  and  oozing 
of  the  blood  in  the  brain,  producing  apoplexy "   (G.  H. 
McMichael,  M.D.).     The  condition  of  the  heart  mentioned 
above  is  called  fatty  degeneration  of  the  heart. 

201.  Hemorrhage  is  a  flow  of    blood  from  an  injured 
blood  vessel.     When  the  wound  is  slight,  the  clotting  of  the 
blood  stops  the  flow.     Clotting   is  rapid  in  the  blood  of 
healthy  persons    and  slow   in  the  blood  of   poorly  nour- 
ished persons.     Blood  does  not  spurt  from  a  cut  vein  but 
flows  in  a  slow  stream.     When  an  artery  is  cut,  the  blood 
comes  forth  in  a  jet,  with  stronger  spurts  at  each  throb  of 
the  heart.     In  a  large  artery  the  pressure  is  so  strong  that 
it  forces  away  the  clot  as  fast  as  it  is  formed,  so  that  death 
may  result  from  loss  of  blood. 

202.  Tobacco  Heart,  or  Trotting  Heart. — Tobacco,  unlike 
alcohol,  does  not  dilate  the  blood  vessels  of  the  skin ;  to- 
bacco users  are  often  pale  from  want  of  blood  in  the  skin. 
We  thus  see  why  tobacco  users  develop  a  stronger  craving 
for  drink  than  non-users,  because  the  alcohol  has,  in  some 
respects,  an  effect  opposite  to  that  of  tobacco.     However, 
heart  action  is  temporarily  increased  when  tobacco  is  used. 
In  the  present  chapter  you  learned  that  the  sympathetic 
nerves  increase  the  heart  action  and  the  vagus  nerves  hold 
ft  in   check.     The    vagus   is    partially   paralyzed    by    to- 
bacco,  and   the    heart   beats    with    more   force,    thus    ex- 
hausting itself.     The  pulse   of   the   habitual   user   shows 
unmistakably  the  injury  done  to  the  heart.     It  loses  the 
firm  steady  beat  of  health  and  becomes  irregular.     Most 
of  the  time  its  beat  is  feeble,  but  for  a  short  period   its 


THE    CIRCULATION  1 15 

beat  may  be  rapid  and  palpitating.  This  condition  is 
known  to  physicians  as  the  "  tobacco  heart."  The  short 
period  of  palpitation  has  caused  it  to  be  named  in  Eng- 
land, the  "  trotting  heart."  Physicians  who  have  made  a 
special  study  of  the  subject,  claim  that  one  out  of  every 
four  tobacco  users  has  the  tobacco  heart.  It  prevents 
success  in  athletic  contests  and  feats  of  strength.  It  pre- 
vented a  large  proportion  of  the  young  men  who  applied 
for  enlistment,  during  the  recent  war  with  Spain,  from 
entering  the  army.  Knowing  the  paramount  importance 
to  sound  health  of  rich  blood  and  perfect  circulation, 
we  are  ftot  surprised  to  know  that  the  whole  body  is 
enfeebled  by  tobacco,  and  that  mental  as  well  as  physical 
vigor  is  impaired.  Observant  teachers  can  often  tell 
which  of  the  boys  in  school  are  addicted  to  the  use  of 
tobacco  from  the  comparative  inferiority  of  their  ap- 
pearance and  from  their  indolence  of  body  and  mind. 

203.  THOUGHT  LESSON.  Comparison  of  Arteries  and 
Veins.  —  (If  this  is  made  a  written  exercise,  underline  the 
words  which  you  supply.) 

Walls.  —  The  walls  of  the are  very  elastic,  while 

the  walls  of  the are  slightly  elastic.  The  walls  of 

the are  thicker  and  stiffer  than  the  walls  of  the . 

It  is  necessary  that  they  should  be  so,  because  they  must 
sustain  the of  the . 

Work  of  each.  —  The  arteries  take  pure  blood  from 

the to  the ,  and  impure  blood  from  the 

to  the .  The  veins  take  pure  blood  from  the 

to  the ,  and  impure  blood  from  the to  the . 

Connections  at  heart.  —  The are  connected  with  the 

auricles.  The are  connected  with  the  ventricles. 

Rate  of  flow.  —  The  blood  flows  more  rapidly  in 
the . 

Manner  of  flow.  —  The  blood  in  the flows  uniformly. 

The  blood  in  the flows . 


1 1 6  ELEMENTS   OF  PH YSIOL OGY 

Control  of  flow.  —  The are  abundantly  supplied  with 

— .     The have  none. 

Location.  —  The  arteries  as   a  general  rule  are  located 
-.     The  veins  are   generally  located .     This  adds 


to  the of  the  body. 

Definitions.  —  The  arteries  are  tubes  that  carry  blood 
(both  pure  and  impure)  to  the . 

The  veins  are  tubes  that  carry  blood  (both  pure  and 
impure)  from  the . 

Accidents.  —  If  an  artery  is  cut,  the  pressure  is  to  be 

applied  -  —  the  cut  and  the .  If  a  vein  is  cut,  the 

pressure  is  to  be  applied  -  —  the  cut.  A  cut  vein  may  be 
told  from  a  cut  artery  in  the  three  following  ways :  — 

204.  Activity  is  the  most  necessary  condition  for  the  health 
of  a  cell.  In  every  cell  is  found  matter  in  three  conditions : 
that  which  is  actually  living,  that  which  was  recently  living, 
and  that  which  is  about  to  live  by  being  transformed  in  the  cell. 
The  transformation  from  lifeless  to  living,  and  from  living  to 
dead,  and  the  removal  of  dead  matter  must  go  on  promptly. 
Anything  which  interferes  with  this  activity  interferes  with 
the  health  of  the  cells.  When  life  is  natural  and  complete, 
all  the  organs  are  given  work  to  do  and  are  healthy,  active, 
and  strong;  there  is  a  feeling  of  buoyant  happiness,  the 
mind  is  clear,  the  will  is  firm,  and  the  man  truly  lives. 

APPLIED   PHYSIOLOGY 
EXERCISE  I 

1.  The  main  arteries  run  down  the  middle  of  each  limb  close  to  the 
bone  on  the  side  toward  which  the  limb  bends.     Why  do  they  have 
this  position? 

2.  Where  is  the  thickest  wall  of  the  heart?     (See  Fig.  85.)     Why? 
The  thinnest  walls?     Why? 

3.  Why  do  we  need  warmer  covering  when  asleep  than  awake? 

4.  When  would  it  be  pleasant  to  throw  off  a  coat  or  cloak,  but 
imprudent  to  do  so? 


THE   CIRCULATION'  1 1/ 

5.  If  the  clothing  has  been  accidentally  wet  and  the  wet  garments 
cannot  be  changed  for  dry  ones  at  once,  how  can  one  keep  up  a  good 
circulation  to  prevent  taking  cold  ? 

6.  Why  does  the  toper  have  a  red  nose? 

7.  When  cold  air  strikes  it,  why  does  the  face  first  blanch  and  then 
flush  (§§  156,  1 60)? 

8.  When  a  person  is  warm-hearted  in  the  usual  sense  of  the  term, 
is  it  also  true  physiologically  ? 

9.  What  is  the  origin   of  the   term  "blue-blooded  aristocracy"? 
When    do  dark  veins  in  the  wrist  show  most  plainly?     Of  what  is 
dark  blood  in  the  body  in  general  a  sign  ? 

10.  Why  does  a  hot  foot-bath  sometimes  relieve  a  headache?    Why 
should  it  relieve  a  cold  in  the  head? 

EXERCISE  H 

1 1 .  Tight  clothing  at  the  waist  may  cause  too  much  blood  in  what 
parts?     Does  it  tend  to  make  the  circulation  sluggish  or  active? 

12.  Which  is  more  compressible,  a  vein  or  an  artery  ?     Does  a  tight 
garter  interfere  more  with  the  flow  of  blood  to  the  feet  or  from  the  feet? 

13.  Why  are  varicose  veins  so  often  found  in  the  lower  leg? 

14.  Why  may  a  sluggish  circulation  through  full  veins  in  the  feet 
as  well  as  want  of  blood  in  the  feet  cause  them  to  be  cold  ? 

15.  Why  are  students  very  likely  to  have  cold  feet? 

1 6.  Why  does  the  body  of  a  person  dying  by  drowning  or  strangula- 
tion turn  blue? 

17.  What  would  you  do  in  the  case  of  a  severe  wound  in  the  absence 
of  a  surgeon  ? 

1 8.  What  is  the  object  of  a  collar?     Why  is  it  therefore  not  neces- 
sary to  have  the  collar  as  high  in  front  as  behind  ?     Why  is  it  unhealth- 
ful  to  have  it  so?     What  is  the  purpose  of  a  cuff? 

19.  What  is  the  most  serious  injury  of  alcohol  to  the  blood? 

20.  In  what  part  of  the  circulation  does  the  so-called  venous  blood 
flow  through  arteries  ? 

EXERCISE  HI 

21.  Show  how  life  comes  by  death  (§  204). 

22.  Can  any  physiological  basis  be  given  for  the  claims  of  patent 
medicine  venders  that  their  nostrums  "purify  the  blood"? 

23.  What  vein  begins  and  ends  with  capillaries  (Fig.  89)  ? 

24.  What  artery  takes  arterial  blood  to  an  organ  where  it  is  still 
further  purified,  yet  is  called  venous  blood  when  it  leaves  the  organ  ? 


ii8  ELEMENTS  OF  PHYSIOLOGY 

(As  it  leaves  that  organ  the  blood  is  the  purest  in  the  body.)     (See 
Plate  V.) 

25.  How  does  alcohol  interfere  with  the  process  of  oxidation? 

26.  What  keeps  the  blood  in  circulation  between  the  beats  of  the 
heart? 

27.  What  are  the  functions  of  the  capillaries? 

28.  Why  does  a  cool  draft  in  the  house  cause  a  cold  quicker  than  a 
cool  wind  out  of  doors? 

29.  Why  do  we  perspire  freely  after  drinking  freely  of  cold  water? 

30.  How  can  an  extensive  burn  cause  death  by  congestion  of  the 
lungs  ? 

31.  What  causes  the  difference  between  the  hard  hand  of  the  black- 
smith and  the  soft  hand  of  the  clerk? 

32.  Why  does  rubbing  wear  out  the  leather  of  the  shoe,  but  the 
friction  of  the  shoe  upon  the  toe  cause  the  skin  to  grow  thicker  and 
to  form  a  corn (§  188)? 

33.  What  is  the  effect  upon  the  circulation  of  traveling  upon  the 
cars  or  in  a  vehicle? 


CHAPTER   IX 


THE  MUSCLES 

205.  It  has  been   learned   that   motion  is   one   of  the 
physiological  properties  of  protoplasm,  along  with  sensi- 
bility and  the  power  of  assimilating 

food.      The  white  blood  cells  have 

a  distinct  motion,  and  certain  cells 

that  line  the  windpipe  and  other 

air  passages  are  able  to  contract 

and  wave   their   cilia,   or  hairlike 

appendages,  to  and  fro.   With  these 

two  exceptions,  the  muscle  cells  are 

the  only  cells  of  the  body  that  have 

a  marked  power  of  contracting  and 

producing  motion.     As  feeling  or 

perceiving  through  the  nerves,  and 

moving  or  exerting  energy  through 

the  muscles,  seem  to  be  the  two 

chief  purposes  of  the  organism,  we  see  how  important  the 

muscles  are  for  the  purposes  of  life.     The  body  has  been 

compared  to  a  steam  engine  but  the  only  object  of   an 

engine  is  to  set  free  energy. 

206.  Kinds    of    Muscles. — Muscular    tissue    occurs    in 
nearly  every  organ.     We  found  that  it  helps  to  form  the 
walls  of  the  blood  vessels,  and  assists  in  the  circulation 
of  the   blood ;    the   eyeballs   are   moved   by   six   sets   of 
muscles;  the  act  of  swallowing  is  performed  by  muscular 
contraction  in  the  gullet;  the  contraction  of  the  muscles 
in  the  walls  of  the  stomach  produces  the  motion  by  which 

119 


FIG.  103.  —  A  Portion  of 
Two  Striated  Muscle  Fi- 
bers, highly  magnified. 

«,  nucleus. 


I2O 


ELEMENTS   OF  PHYSIOLOGY 


the  food  is  mixed  ;  in  the  intestines  the  muscles  keep  the 
partly  digested  food  in  motion  ;  the  muscles  in  the  limbs 
enable  us  to  move  and  work  ;  the 
heart  is  chiefly  muscle  ;  the  muscles 
in  the  chest  and  trunk  enable  us  to 
breathe  ;  those  in  the  larynx  are  used 
in  talking.  Muscles  have  been  divided 
into  two  classes,  voluntary  and  invol- 
untary. The  first  class  is  under  the 
control  of  the  will,  either  at  all  times 
or  part  of  the  time  :  the  second  is 
never  under  the  control  of  the  will  ; 
their  work  goes  on  quite  independ- 
ently of  the  will  and  even  during 
sleep.  Can  you  assign  to  their  proper 
classes  the  muscles  that  have  been 
named  in  this  paragraph  ? 

207.  Structure  of  Muscles.  —  In 
studying  the  master  tissues  we 
studied  muscular  tissue  in  general, 
and  learned  how  a  muscle  is  able 
to  shorten.  The  contraction  of  a 
muscle  is  caused  by  the  contraction 

showing  the  capillary  vessels    °f    the    individual    fiber-cells    which 
compose  it.     Each  fiber  shortens  in 

length  and  becomes  proportionally  thicker  ;  the  sum  total 
of  the  contractions  of  these  fiber-cells  taking  place  at  the 
same  time,  makes  up  the  contraction  of  the  whole  muscle. 
The  number  of  fibers  lying  side  by  side  determines  the 
thickness  of  the  muscle,  and  the  amount  of  strength  with 
which  it  can  contract  ;  while  the  number  of  fibers  lying  end 
to  end  determines  the  amount  of  shortening  or  contraction 
of  which  the  muscle  is  capable.  When  a  muscle  is  habitu- 
ally used,  it  becomes  larger,  firmer,  darker,  and  stronger. 
208.  Voluntary  and  involuntary  muscles  are  not  con- 


, 

FIG.    104.  —  A    Portion    of 

Three   striated    Muscle 


THE  MUSCLES 


121 


FIG.  105.  —  Fibers  of  Non-striated  Mus- 
cles, or  Involuntary  Muscles. 


structed  exactly  alike.     Examined  under  the  microscope, 
each   fiber   of   a  voluntary  muscle   shows   bright    bands 

alternating  with  dark  bands, 
running  across  it  (Fig.  103). 
These  bands  give  the  whole 
muscle  a  striated  or  striped 
appearance  under  the  mi- 
croscope, hence  this  kind 
of  muscle  is  called  striated 
muscle  (Fig.  104).  The  fi- 
bers are  bound  together  by 
connective  tissue  into  bundles  called  fascicles  and  these 
again  into  larger  bundles.  The  connective  tissue  surround- 
ing the  bundles  can  be  plainly  seen  in 
chipped  beef,  also  in  fresh  beef  and 
boiled  beef.  The  voluntary  muscles  are 
darker  red  than  the  involuntary.  Lean 
meat  is  made  up  of  these  muscles.  They 
are  near  the  surface,  but  their  outlines 
under  the  skin  are  obscured  to  a  greater 
or  less  degree  in  different  persons,  ac- 
cording to  the  thickness  of  the  layer  of 
fat  between  the  muscles  and  the  skin. 
These  muscles  are  usually  attached  to 
bones.  They  contract  quickly,  while 
the  involuntary  muscles  contract  slowly. 
209.  Involuntary  Muscles  are  found 
in  the  walls  of  the  alimentary  canal,  the 
bladder,  the  gullet  and  several  other 
organs  ;  all  such  muscles  are  composed 
of  fibers  which  are  not  striated,  and  are,  therefore,  called 
plain  muscle  fibers.  A  striated  fiber  is  about  one  inch  in 
length  and  yj^  of  an  inch  in  thickness  and  is  shaped  some- 
what like  a  cylinder ;  it  possesses  several  nuclei.  A  plain 
muscle  fiber  is  not  more  than  ^^U-  of  an  inch  in  length, 


FIG.  106.  —  Two  Cardiac 
Muscle  Fibers. 

«,  nucleus;  /,  line  of  junc- 
tion between  the  two  cells  ; 
/,  process  joining  a  simi- 
lar process  of  another  cell. 
(Magnified  400  diameters.) 


122  ELEMENTS   OF  PHYSIOLOGY 

has  the  form  of  a  very  slender  spindle,  and  contains  one 
nucleus  (Figs.  27,  105).  The  fibers  interlace  and  are  held 
together  by  fine  connective  tissue  to  make  the  hollow, 
slow,  involuntary  muscles. 

210.  Cardiac  Muscular  Tissue,  of  which  the  heart  con- 
sists, differs  from  both  striated  and  plain  muscular  tissue 
(Fig.    106).      Its   fibers   possess   one   nucleus,    like   plain 
fibers ;  they  are  not  spindle-shaped  and  narrow,  however, 
but  broader  and  cylindrical.      They  are,  moreover,  faintly 
cross-striated  by  light  and  dark  bands.    We  may  say,  there- 
fore, that  although  the  heart  is  in  every  respect  an  involun- 
tary muscle,  it  has  more  resemblance  to  striated  than  to 
plain  muscle.     The  many  muscles  used  in  breathing  are  at 
times  voluntary,  and  at  other  times  involuntary ;  but  they 
are  all  striated  muscles  with  the  usual  structure. 

211.  THOUGHT  LESSON.     Effects  of  Unhygienic  Shoes.  — 

1.  What  the  faults  of  shoes 
may  be  (in  shape,  size,  sole,  heel, 
toe,  and  instep). 

2.  Deformities     resulting    to 
foot  (skin  of  foot,  nails,  joints, 
arch,  instep,  and  ankle). 

3.  Effects  of  improper  shoes 
on  habits  of  life. 

FIG.  107.  -  A  Natural  Foot.  4-  Effect  on  particular  organs 

or  functions. 

5.  Gain  and  loss  to  personal  appearance  from  wearing 
improper  shoes. 

6.  Effect  on  mind  and  disposition. 

7.  If  a  shoe  is  too  loose,  it  slips  up  and  down  at  the  heel 
and  chafes  the  skin  there.     If  too  tight,  there  is  pressure 
on  the  toes,  which  causes  a  corn  or  ingrowing  nail.     Have 
your  shoes  been  correct  or  have  they  been  too  loose  or  too 
tight  ?     What  proportion  of  people  wear  shoes  that  are  too 
tight  ? 


THE  MUSCLES 


123 


FIG.  108.  — A  Deformed 
Foot  in  an  Unhygienic 
Shoe. 


FIG.  109.  — The  Natural 
Shape  of  the  Sole. 


FIG.  no.  —  Showing  the 
Toes  unduly  crowded, 
with  Corns,  caused  by 
Tight  Shoes. 


FIG.  in.— The  Track 
made  by  a  Natural 
Foot.  Make  a  test 
by  wetting  your  bare 
foot  and  noticing 
the  track  made  upon 
the  floor. 


FIG.  ii2.  — The  Traik 
made  by  a  Foot  in 
which  the  Natural 
Arch  has  been  partly 
broken  down  by 
Tight  Shoes. 

If  the  arch  breaks  down 
entirely  the  foot  is  called 
"  flat  foot." 


FIG.    113.  — Sole    of 
Foot. 

Showing  some  of  the 
muscles  and  tendons 
that  bend  the  toes. 


124  ELEMENTS   OF  PHYSIOLOGY 

8.  How  many  sprained  ankles   have  you  known  of? 
Were  the  sufferers  mostly  boys  or  girls  ?     Why  ? 

Most  people   assume  the  following  rule  in  selecting  a 
shoe  :     If  you  can  just  draw  on  a  shoe  without  much  effort 

and  sit  with  it  on  the  foot  for 
ten  minutes,  it  will  be  comfort- 
able to  walk  in  and  wear  all  day. 
Yet  such  a  shoe  is  one  size  too 
FIG.  n4.-skeieton  of  F^ol  if  small  for  walking.  Many  mak- 


the  child  never  goes  barefooted,     ers  no  longer  number  their  shoes 

the  arch   is    likely   to  become  . 

flattened  instead  of  high.  plainly  because  of  the  vanity  of 

some  purchasers.     A  new  shoe 
should  be  as  comfortable  as  an  old  one. 

9.  What  is  the  general  arrangement  of  the  bones  of  the 
foot  ?  Does  the  weight  of  the  body  come  upon  the  middle 
of  the  arch  ?  How  can  this  arch  be  injured  and  what  is 
such  a  deformity  called  ? 

10.  Why  is  it  that  people  who  grow  up  in  warm  climates 
are  more  likely  to  have  high  arched  insteps  and  elastic 
feet  than  those  who  pass  their  childhood  in  cold  cli- 
mates ? 

Persons  who,  because  of  silly  jokes  about  big  feet  or  for 
other  reasons,  have  the  idea  that  the  shoe  should  leave  no 
extra  room,  but  should  fit  as  if  it  were  covering  a  wooden 
foot,  will  always  get  uncomfortable  shoes. 

212.  THOUGHT    LESSON.      Compare  the  voluntary  and 
involuntary  muscles  by  writing  in  two  columns  headed, 
Voluntary  Muscles  and  Involuntary  Muscles,  the  facts  con- 
cerning their  Control,  Structure,  Color,   Position  in  Body, 
Attachment,    Rate    of    Contraction,    Number    of    Nuclei, 
Length   of    Fibers,  Breadth   of  Fibers,  Shape  of  Fibers. 
(Place  these  titles  in  a  third  column.) 

213.  The    Attachment   of    Muscles.  —  The    involuntary 
muscles  are  usually  tubular  or  hollow,  and  surround  the 
internal  organs.     They  are  sometimes  called  the  visceral 


THE  MUSCLES 


125 


muscles  because  the  internal  organs  are  called  the  viscera. 
The  quicker,  stronger-acting  voluntary  mus- 
cles are  sometimes  called  the  skeletal  muscles 
because  nearly  all  of  them  are  attached  to 
bones.  Exceptions  to  this  are  the  sphincter 
muscles  or  circular  muscles  that  surround 
orifices,  as  the  muscles  that  pucker  the 
mouth  and  squint  the  eye.  There  are  about 
five  hundred  voluntary  muscles.  By  study- 
ing the  figures  you  will  notice  that  the  mid- 
dle portion  of  these  muscles  is  usually  large 
and  full,  and  that  the  muscles  taper  to  small 
cords  at  the  ends  (Fig.  113,  etc.).  The 

FIG.  115.— Striated  v 

Muscular  Fibers  muscles  of  the  calf  move  the  foot,  and  the 
(a)    terminating  muscies  of  the  forearm  move  the  hand.     If 

in  lendon  (o). 

the  full  round  muscles  extended  down  over 
the  wrists  and  ankles,  it  would  make  these  as  large  around 
as  the  forearm  or  calf, 
and  the  wrists  and 
ankles  would  be  very 
clumsy  and  awkward. 
It  is  found  that  the  con- 
nective tissue  which 
binds  the  fibers  of  a  mus- 
cle into  bundles  and  forms 
sheaths  for  the  bundles, 
extends  beyond  the  mus- 
cular tissue  and  unites  to 
form  a  dense,  inelastic, 

White 

a       tendon 
.  \  .-i-,,  rv 

115).  The  fibers  are 
very  closely  packed  together  and  make  a  very  strong  cord. 
One  no  thicker  than  a  lead  pencil  is  strong  enough  to 
support  twice  the  weight  of  the  body.  A  tendon  contains 


FlG.  116.  —  Diagram  to  show  the  Action  of  the 
Biceps  Muscle  of  the  Arm. 

COrd    The  two  tendons  by  which  the  muscle  is  attached  to 
the  scapula  are  seen  at  a ;  P,  the  point  of  attach- 
(Fig.        ment  of  the  muscle  to  the  radius;    Ft  the  elbow 
joint;    W,  the  weight  of  the  hand. 


126 


ELEMENTS   OF  PHYSIOLOGY 


no  nerves  and  very  few  blood  vessels.  Some  muscles 
have  a  tendon  at  only  one  end ;  some  have  no  tendon  but 
are  attached  directly  to  bones.  Find  muscles  without 
tendons  by  studying  the  figures.  The  cordlike  nature  of 
tendons  can  be  ascertained  by  feeling  the  tendons  under 
the  knees,  called  hamstrings,  or  the  tendons  in  the  angle 
of  the  elbow. 


4 


FIG.  117.  —  Tapping 
Floor  with  Toe. 
Lever  of  first  order. 


FIG.  118.  —  Raising 
Weight  of  Body 
upon  Ankle. 

Lever  of  second  order. 


FIG.  119.— Raising 
a  Weight  upon 
Toes. 

Lever  of  third  order. 


214.  How  Muscles   and   Bones   Cooperate.  —  When   you 
grasp  a  heavy  weight  in  the  hand  and  lift  it  by  bending  the 
elbow,  where  is  the  muscle  that  does  the  work  ?     You  will 
easily  find  it  in  the  upper  arm  ;  this  muscle  is  called  the 
biceps  because  it  is  attached  to  the  shoulder  blade  above  by 
two  tendons.     The  lower  arm   acts  as  a  lever  with  the 
fulcrum,  or  fixed  point  of  the  lever,  at  the  elbow  (Fig.  1 16). 
It  is  easy  to  see  that  a  slight  contraction  of  the  biceps 
muscle  will  move  the  weight  a   greater   distance  than   is 
accounted  for  by  the  shortening  caused  by  the  actual  con- 
traction of  the   muscle.     This  is  what  the  bones  usually 
accomplish  for  the  muscles;  they  change  a  slow,  short, 
inadequate  movement  into  a  long,  swift  movement.    While 
the  muscle  contracts  an  inch,  the  bone  may  move  a  foot. 
The  bones  thus  add  greatly  to  the  range  and  rate  of  motion. 

215,  Figures  117,  118,  and  119  show  the  three  orders  of 
levers.     In  the  lever  of  the  first  order,  the  fulcrum  (F)  is 


THE  MUSCLES 


127 


7 


between  the  power  (P)  and  the  weight  (  W).     In  the  lever 

of  the  second  order  the  weight  is  between  the  other  two,  and 

in  the  lever  of  the  third  order  the  power 

is  between  the  others.      In  Fig.   116  the 

biceps  muscle  acts  on  the  radius  and  ulna 

fastened  together  as  one,  turning  at  the 

elbow   as    a    fulcrum ;    the   weight   to    be 

lifted  is  in  the  hand.     This  is  evidently  a 

lever  of  the  third  order  with  the  power 

between  the  other  points.     In  this  case  it 

takes  a  force  in  the  muscle  equal  to  about 

six  pounds  to  raise  one  pound  in  the  hand. 

216.  Figure  120  shows  how  the  muscles 
may  act  as  levers  upon  the  bones  to  pre- 
vent the  bones  from  turning  upon  the  joints 
as  fulcrums;  thus  the  body  is  held  erect. 
Where  are  the  muscles  located  that  keep 
the  body  from  falling  or  bending  forward 
(Fig.     120)?      From     falling     backward? 
(Which  of  the  two  sets  is  in  front  ?)     What 
kind  of  lever  is  illustrated  by  the  head  tilted 
upon  the  atlas  (Fig.  121)? 

217.  Names  and  Positions  of  Muscles. — 
A  few  of  the  important  muscles  are  here 
mentioned:    The  scalp   muscle  (Fig.   122) 

passes  over  the  top  of  the  head ;  it  raises  FlG-  I20.— Diagram 
the  skin  over  the  eyes,  and  (in  some 
persons)  moves  the  scalp.  The  two  pairs 
of  chewing  muscles  are  the  temporal  and 
masseter  (Fig.  122).  You  can  feel  the  temporal  muscle 
swell  and  harden  if  you  place  your  finger  on  the  temple  and 
close  your  mouth  forcibly.  In  the  same  manner  you  may 
feel  the  contraction  of  the  masseter  by  placing  the  fingers 
just  below  the  cheek  bone.  The  muscle  used  in  bowing 
passes  obliquely  down  on  the  side  of  the  neck  to  the 


of  the  Muscles  that 
keep  the  Body 
erect. 


128 


ELEMENTS   OF  PHYSIOLOGY 


collar  bone  (Fig.   124).      It  can  be  felt  as  a  thick  band; 

when  the   head  is  turned  to  one  side,  it  stands  out  as  a 

ridge.     When  one  of  the  two  acts  alone, 

it  tu:ns  the  face  so  as  to  look  to  the  other 

side.     When  both  act  they  bow  the  head. 

The  deltoid  (Figs.    123,    124),  or  shoulder 

cap  muscle,  raises  the  whole  arm  outward 

and  upward  from  the  side.     Can  you  locate 

it  by  the  feeling  of  fatigue   after  raising 

the  arm  twenty  times  ?      The  biceps    can      tilt'ed  upo'n  Atlaes* 

be  seen  and  felt  contracting  on  the  front 

of  the  arm  when   bent  at  the  elbow.     The  triceps  is  on 

the  opposite  side  of  the  arm  and  straightens  the  elbow 


TRAPEZIUS 
DELT0/& 


FIG.  122.  —  Muscles  of  Head  and 
Neck.  Find  the  following  mus- 
cles :  — 

Chewing  muscles;  scalp  muscles;  bow- 
ing muscle  of  one  side;  muscle  that 
holds  head  erect  (upper  part  of 
trapezius  at  back  of  neck) ;  muscle 
that  squints  the  eye  ;  muscle  that 
pouts  the  lips;  muscle  that  broadens 
the  mouth  in  smiling;  muscle  that 
raises  corners  of  mouth ;  muscle  that 
draws  down  corner  of  mouth. 


FIG.    123.— Principal   Muscles  of  the 
Back. 

Trapezius  draws  shoulder  and  head  back  ; 
deltoid  raises  whole  arm  ;  latissimus, 
climbing  muscle,  ©bliquus  internus  and 
obliquus  externus  draw  abdominal  wall 
in  and  force  abdominal  contents  against 
the  diaphragm,  thus  expelling  air  from 
lungs. 


THE  MUSCLES 


I29 


(Figs.  124,  125).  Which  is  used  in  striking  a  blow,  the 
biceps  or  the  triceps  ? 

218.  The  sartorius  ("tailor")  muscle  (Fig.  126)  is  nearly 
two  feet  long  and  is  the  longest  muscle  in  the  body  ;  it  passes 
from   the  outer  side  of 

the  hip  bone  to  the  inner 
side  of  the  leg  below  the 
knee,  and  is  used  in 
crossing  the  leg;  because 
of  the  position  assumed 
by  a  tailor  at  work  it  is 
named  the  tailor's  mus- 
cle. The  gastrocnemius 
is  a  thick  muscle  in  the 
calf  of  the  leg,  and  raises 
the  heel  (Fig.  125). 
When  is  it  used  ?  It  is 
attached  to  the  heel  by 
the  largest  tendon  in  the 
body,  called  the  "tendon 

Of    Achilles."       Ask    the    Fia    124- -  Superficial    View    of  Muscles   of 

Upper     Part    of    Trunk,     from     the    front, 
teacher     why      it     IS       SO        (Allen  Thomson.) 

called ;  or  read  the  story 
of  Achilles. 

219.  The       trapezius 
("four-sided")       (Figs. 
123,     125)    is     a    large 

muscle  covering  the  back  between  the  shoulders.  It 
draws  the  shoulders  back  and  holds  up  the  head.  Can 
you  find  the  climbing  muscle  (Figs.  123,  124),  or  the 
muscle  that  draws  the  arm  backward  and  downward  (latis- 
simus  or  "broadest")?  When  a  person  hangs  by  the 
hands,  it  helps  to  raise  the  body.  It  is  a  large  spread- 
out  muscle  extending  from  the  humerus  to  the  vertebral 
column. 


sterno-mastoid  of  the  left  side;  5,  trapezius  ;  6, 
deltoid  ;  7,  upper  part  of  triceps  in  the  left  arm  ; 
10,  latissimus  dorsi  ;  n,  pectoralis  major  ;  n',  on 
the  right  side,  its  clavicular  portion  ;  12,  part  of 
pectoralis  minor ;  13,  serratus  magnus  ;  14,  ex- 
ternal oblique  muscle  of  the  abdomen  ;  15,  placed 
on  the  tip  of  the  sternum. 


130 


ELEMENTS   OF  PHYSIOLOGY 


220.  Each  muscle  has  another  muscle  or  other  muscles 
that  can  undo  the  work  done  by  it.  Two  muscles  with  oppo- 
site action  or  function  are  said  to  be  antagonists.  There  is  a 
great  fan-shaped  muscle  called  \hzpectoralis  (n,  Fig.  124) 


Cittnion  of  tht  Hind 


FlG.  125.  —  Full  Figure  Muscles  (rear). 

on  the  chest,  extending  from  the  sternum  to  the  arm.  It 
draws  the  arm  downward  and  inward.  This  muscle  is  very 
large  in  birds  and  is  used  in  flying.  To  what  muscle  is  it 
an  antagonist  ?  Muscles  that  bend  joints  are  called  flexors. 
Those  that  straighten  joints  are  called  extensors.  To  which 
kind  does  the  biceps  belong  ?  Which  extensor  muscle  is  its 
antagonist? 


THE  MUSCLES 


221.  Muscles  are  named  from :  their  shape,  as  deltoid 
(like  the  Greek  letter  delta,  A  ;  their  location,  as  tibialis  (near 
the  tibia) ;  their  action,  as  flexors  ;  their  manner  of  attach- 
ment, as  triceps  (three-headed). 


.Extensors  of  tht  Hand 
-  -  .  -  £le*on  of  the  Hind 


E«te«sor,  of  th.  Tew 


FIG.  126.  —  Full-figure  Muscles  (front). 

222.  THOUGHT  LESSON.  Anatomy  and  Physiology  of 
Muscles.  —  By  studying  the  figures,  apply  these  four  pairs  of 
adjectives  in  their  proper  places  in  the  lines  below  :  long  and 
round  ;  thin  and  flat ;  short  and  narrow  ;  broad  and  flat :  — 

i.    The  muscles  of  the  face  are and . 

The  muscles  of  the  cranium  are and . 


132  ELEMENTS   OF  PHYSIOLOGY 

The  muscles  of  the  trunk  are and . 

The  muscles  of  the  limbs  are and . 

2.  Grasp  your  arm  above  the  elbow  and  bend  it.    What 
changes  do  you  feel  ? 

3.  Span  the  biceps,  holding  tip  of  finger  in  elbow  and 
thumb  farther  up  the  arm.     About  how  many  inches  of  its 
length  does  the  biceps  lose  by  contracting? 

4.  What  muscles  are  attached  to  the  bones  without  ten- 
dons ?     (Examine  figures  in  book;  also  think  of  meat  you 
have  eaten.) 

5.  Why -is  round  steak  usually  the  toughest  steak  ?   the 
most  nutritious  ? 

6.  Why  is  a  fowl's  leg  dark  meat  although  its  breast  is 
white  ?     Why  is  a  fowl's  breast  white  and  a  dove's  breast 
dark  (§§  207,  220)? 

7.  Why  does  practicing  looking  cross-eyed  have  a  tend- 
ency to  make  one  so  ?     (Give  effect  on  both  nerve  and 
muscle.) 

8.  Where  are  the  muscles  that  bend  the  fingers  ? 

9.  Name  the  places  in  the  body  where  the  tendons  can 
be  most  easily  felt  while  the  muscles  are  working. 

223.  How    the   Nerves    and    Muscles  cooperate.  —  How 
many  ways  of  exciting  the  contractility  of  a  muscle  have 
you   learned  ?     When  the  food  enters  the  stomach,  the 
mechanical   stimulus    starts   impulses  along  the  nerve  to 
the  ganglion,  and  reflex   impulses  cause  the   involuntary 
muscles  in  the  walls  of  the  stomach  to  contract.     When 
we   desire    to  make   a   certain  movement,    an   impulse   is 
sent  from  the  brain  along  a   nerve  to  the  muscle  which 
performs  this  movement.     This  impulse  sets   the  muscle 
engine  going  somewhat   as  an   electric    current    sent  by 
pressing  .a  button  starts  a  bell  to  ringing  or  a  machine  to 
running. 

224.  The  muscular  tissue  is  composed  chiefly  of  albu- 
minous material.     It  has  been  found  that  increased  muscular 


THE  MUSCLES  133 

action,  such  as  mountain  climbing,  hardly  increases  the 
amount  of  albuminous  material  (urea)  excreted  as  waste. 
Such  activity,  however,  does  largely  increase  the  amount 
of  carbon  dioxid  given  off.  It  is  believed,  therefore,  that 
our  energy  is  largely  derived  from  starches  and  sugars 
(carbohydrates)  and  fats.  The  fact  that  beasts  of  burden 
depend  chiefly  upon  carbohydrate  foods  strengthens  this 
view.  That  muscles  use  sugar  in  their  action  is  indicated 
by  the  fact  that  the  arteries  take  more  sugar  to  the  muscles 
than  is  carried  away  from  them  by  the  veins. 

225.  The  nerve  impulse  reaching  the  muscle  causes  it  to 
contract.  This  takes  about  ^V  °f  a  second.  It  would  relax 
in  gV  °f  a  second  also,  and  it  can  be  kept  in  a  state  of  con- 
traction only  by  successive  impulses,  usually  about  10  per 
second.  Thus  it  remains  in  a  tremulous  state  of  contraction. 
The  vibrations  may  become  apparent  during  excitement, 
or  when  a  great  effort  is  being  made.  If  a  muscle  con- 
tracts continuously  for  a  long  time,  a  time  comes  when 
it  can  no  longer  be  made  to  contract,  not  even  by  an 
electric  stimulus,  but  it  becomes  soft  and  relaxed.  What 
is  the  cause  of  this  ?  Are  the  oxygen  and  sugar  and  fat  all 
combined  and  changed  into  carbon  dioxid  ?  Or,  as  we 
say,  is  the  strength  all  used  up  ?  No,  it  is  found  that  if 
the  carbon  dioxid  is  allowed  to  escape  but  no  fresh  blood 
allowed  to  come,  the  muscle  can  be  made  to  contract  again. 
This  shows  that  the  accumulation  of  the  carbon  dioxid 
gas  and  perhaps  some  acids  besides,  prevent  the  nerve 
stimulus  from  having  effect.  The  paralysis  and  aching  of 
extreme  fatigue  are  thus  caused.  It  is  a  very  beneficent 
thing  that  a  healthy  person  undisturbed  by  poisonous  drugs 
or  stimulants  can  never  use  up  all  his  strength.  A  man 
may  have  been  ill  for  weeks,  yet  when  delirious,  and  stimu- 
lated by  the  poisons  formed  in  the  course  of  the  disease,  he 
proves  that  he  still  has  strength  enough  to  overpower 
several  strong  men. 


134  ELEMENTS   OF  PHYSIOLOGY 

226.  Coordination  of  Several  Muscles.  —  Would  you  like 
to  see  two  persons  try  to  thread  a  needle,  one  holding  the 
thread  and  the  other  the  needle  ?     Would  they  succeed 
well  ?     Or  in  so  simple  a  matter  as  the  use  of  the  knife  and 
fork  in  eating,  could  it  be  easily  done  if  one  holds  the  piece 
of  meat  with  the  fork  while  the  other  tries  to  cut  it  ?     Why 
is  it  that  the  right  hands  of  two  persons  cannot  work  so 
well  together  as  the  right  and  left  hands  of  one  person  ? 
It  is  because  of  the  nervous  connection  between  the  hands 
of  the  same  person,  so  that  one  hand  knows  just  what  the 
other  is  doing.     Let  us  think  of  what  takes  place  in  our 
bodies  when  we  throw  a  stone  at  a  mark.     At  the  same  time 
we  see  the  mark,  hold  the  stone  in  the  hand  and  throw  it. 
In  throwing  a  stone,  at  least  a  dozen  muscles  are  used. 
Each  one  of  these  must   contract   at  the  right  time  and 
in  the  right  way,  or  the  stone  will  miss  the  mark.     Each 
muscle  shortens    under  the  influence  of  a  nerve  impulse 
brought  from  the  brain  by  a  motor  nerve.     If  one  muscle 
shortens  an  instant  too  soon,  or  a  little  too  much,  the  stone 
goes  to  one  side.     This  working  together  of  the  muscles  by 
the  aid  of  the  nerves  is  called  coordination.     Coordination 
is  necessary,  even  in  standing  erect. 

227.  Nerve  Expenditure.  —  It  is  found  that  the  use  of 
many  small  muscles  is  much  more  exhausting  than  the  use 
of  a  few  larger  ones.      This  is  on  account  of  the  nerve 
energy  consumed.      A  drummer  beating  a  big  bass  drum 
may  do  more  muscular  work  than  one  who  plays  a  tune 
softly  on  the  piano,  but  the  piano  playing  exhausts  the 
performer  much  sooner.     This  is  because  the  movements 
of  the  wrist  and  fingers  employ  thirty  muscles  and  a  great 
number  of  nerves.     The  striking  of  the  keys  with  the  ends 
of  the  fingers  where  some  of  the  most  sensitive  nerves  of 
the  body  terminate,  may  have  some  effect  also,  and  may 
help  to   explain  why  so  many  persons,  especially  young 
ladies,  who  take  little  other  exercise,  have  become  nervous 


THE  MUSCLES  135 

wrecks  from  piano  playing.  The  typewriter  has  one  of 
the  objections  named  above,  but  it  has  the  advantage  over 
the  pen  of  giving  some  variety  of  motion  compared  to  the 
monotonous  use  of  the  same  muscles  in  penmanship. 

228.  Habitual  Over-expenditure  of  Nervous  and  Muscular 
Energy.  —  The  fact  that  the  muscles  are  arranged  in  pairs 
as  antagonists  of  each  other  may  have  a  calamitous  effect 
in  the  case  of  persons  with  ill-regulated  nervous  systems. 
Such  persons,  on  account  of  anxiety  or  worry,  doubt,  or 
overactive  desire,  keep  their  muscles  drawn  tense,  the  an- 
tagonists pulling  against  each  other,  and  after  awhile  they 
lose  the  power  of  relaxing  their  muscles.     They  wear  anx- 
ious expressions,  because  the  muscles  of  the  face  are  never 
relaxed  or  in  repose.     Their  movements  are  nervous   and 
jerky  instead  of  graceful  and  easy.     Their  breathing  is  not 
deep    and   natural,    because    the   breathing    muscles   pull 
against  each  other,  and  their  voices,  therefore,  are  not  even 
and  steady.     They  cannot  be  perfectly  still,  but  chew  gum 
or  a  pencil,  rock  the  chair,  pull  the  mustache,  etc.     Do  you 
know  of  any  of  your  friends  who  are  handicapped  by  this 
condition  of  over-tension  ?     When  such  people  listen  to  a 
sermon  their  backs  get  tired  because  they  cannot  relax  com- 
fortably to  the  seat  and  use  their  ears  only  while  listening. 
When  they  lie  down,  they  try  to  hold  the  body  on  the  bed, 
and  they  keep  the  muscles  of  the  neck  tense  as  if  trying 
to  hold  the  head  on  the  shoulders.     Such  persons  should 
lie  down  for  ten  minutes  twice  a  day  and  have  an  assistant 
make  a  test  to  ascertain  whether  they  are  thoroughly  re- 
laxed ;  let  the  assistant  lift  one  arm  and  see  whether  it  will 
drop  as  if  lifeless  when  released,  or  fall  like  a  rope  when 
flung  to  one  side ;  let  him  find  out  also  whether  the  head 
is  relaxed  on  the  shoulders. 

229.  Over- tension   is    common    to    adults  in  cold    cli- 
mates, but  is  also  known  in  warm  climates.     A  graceful 
person,   like  a  child,  uses  just  the  muscles  necessary  for 


136  ELEMENTS   OF  PHYSIOLOGY 

any  act,  and  no  more.  Ease  of  manner,  as  well  as  health, 
make  important  the  correction  of  conditions  to  which  all 
hurrying,  ambitious  persons  are  liable  in  an  age  of  keen 
competition  and  of  ambition  for  learning  and  distinction. 
Above  all,  repose  of  spirit  and  contentment  of  mind  bring 
grace  and  ease  of  body. 

230.  Muscular  Tone.  —  That  the  muscles  may  be  always 
ready  for  use,  they  must  not  be  entirely  soft  and  flabby, 
but  under  a  condition  of  very  slight  contraction  called  tone. 
We  find  that  the  muscular  walls  of  the  blood  vessels  possess 
tone.     It  is  this  condition  of  slight  contraction  which  causes 
a  wound  in  the  flesh  to  gape  open.     If  a  tendon  is  cut,  the 
muscle   shortens  on  account   of   its   tone.     If  the  nerve 
going  to  the  muscle  is  cut,  the  muscle  lengthens   a   little, 
that  is,  it  relaxes,  showing  that  there  must  be  faint  but  con- 
stant  impulses  coming   through   the   nerve   to   keep  the 
muscle  in  tone.     When  one  is  asleep  the  body  does  not 
lie  perfectly  straight,  but  the  joints  are  slightly  bent  to 
allow  relaxation. 

231.  THOUGHT    LESSON.      Physiology    of    the    Circula- 
tion.—  i.  What  do  you  notice  after  muscular  exercise  that 
leads  you  to  think  that  it  makes  the  blood  flow  faster? 

2.  What  must  be  the  effect  in  a  vein  when  a  contracting 
muscle  presses  upon  it  ?     Why  does  this  aid  the  blood-flow 
in  only  one  direction  ? 

3.  What  shows  that  exercise  lessens  the  work  of  the  heart  ? 

4.  Why  is  standing  still  more  tiresome  than  walking  ? 

5.  Why  is  there  need  for  valves  in  the  veins  (§  167)? 

6.  Why  is  the  activity  of  the  kidneys  greater  in  winter 
than  in  summer,  while  with  the  skin  the  reverse  is  true 

(§417)? 

232.  Physiological  Effects  of  Muscular  Activity.  —  It  has 
been  explained  how,  during  exercise,  each  muscle  becomes, 
as  it  were,  a  throbbing  heart,  squeezing  the  blood  tubes 
empty  while  contracting,  and  then  relaxing  and  allowing 


THE  MUSCLES  137 

them  to  fill  up  anew.  This  pumping  is  done  by  the  pres- 
sure of  the  thickened  muscle  fibers  on  the  veins,  the  flow 
being  controlled  by  the  valves.  It  has  been  actually  ob- 
served that  the  quantity  of  blood  flowing  through  one  of  a 
horse's  muscles  used  in  eating,  was  three  times  as  great 
when  the  animal  was  engaged  in  chewing  oats  as  when  the 
muscle  was  at  rest.  This  powerful  effect  upon  the  circula- 
tion causes  renewed  nutriment  to  reach  every  neighboring 
organ  and  tissue,  and  the  waste  material  to  be  removed. 
Through  the  effects  of  exercise  upon  the  circulation,  the 
body  is  thus  purified  and  made  sound  and  strong  (Fig.  128). 

233.  An  Aid  to  the  Memory.  —  In  tracing  the  effect  of 
muscular  work  upon  the  different  organs,  let  us  take  them 
in  the  order  in  which  the  organs  are  located  in  the  body. 
Let  us  go  in  order  from  the  outer  organs  to  the  deeper  ones, 
viz  :  skin,  fat,  muscles,  skeleton,  viscera.     The  viscera  will 
then  be  taken  in  order,  beginning  with  the  highest,  viz : 
brain,  lungs,    heart,  digestive  organs,  and  lastly,  general 
effects.    By  using  this  fixed  order,  all  can  be  called  to  mind 
without  omission.     It  is  recommended  to  the  pupil  that  he 
group  other  series  of  topics  in  his  memory  in  the  same  way, , 
thus  keeping  the  mental  eye  upon  the  body  instead  of  upon 
the  pages  of  the  book. 

234.  The  Nine  Effects  of  Muscular  Exercise  enumerated 
in  order  are  as  follows  :  — 

1.  The  Skin.  —  It  opens   the   pores   of    the    skin  with 
perspiration,    fills   the   capillaries   with   fresh   blood,    and 
improves  the  complexion  by  making  the  skin  fresh,  pink, 
and  smooth. 

2.  The  Fat.  —  In  cases  of  undue  accumulation  of  fat,  the 
fat  is  burned  up,  and  in  cases  of  too  great  leanness,  muscu- 
lar exercise,  by  means  of  improved  digestion  and  circulation 
causes  the  fat  to  increase  to  the  proper  amount. 

3.  The   Muscles.  —  Muscles  affect  themselves  through 
the    improved   circulation,    and   even    the    weakest    and 


138  ELEMENTS   OF  PHYSIOLOGY 

thinnest  muscles  will  grow  large  and  strong,  and  the 
flabbiest  muscles  will  acquire  a  healthy  tone,  through 
regular  use.  The  condition  of  an  arm  carried  in  a  sling  is 
an  illustration  of  the  effects  of  disuse. 

4.  The  Skeleton.  —  The  bones  are  better  nourished,  but 
the  chief  benefit  of  exercise  to  them  comes  through  the 
improved   strength   and   tone   of  the    muscles   by   which 
the  bones   are  held  in  proper  position.      Thus  deformed 
cartilages  and  stretched  ligaments,  with  the  accompanying 
round  shoulders,  flat  chest,  and  spinal  curvature  are  pre- 
vented.    A   person   with  good  muscles   sits,    stands,  and 
carries  himself  erect.     One  with  weak  muscles  is  apt  to 
slouch  down. 

5.  The  Brain.  —  The  aid  given  to  the  heart  by  the  con- 
traction of  the  muscles  makes  the  blood  bound  forward  in 
the  vessels,  and  the  pure  fresh  blood  enables  the  brain  to 
work  with  greater  ease  and  pleasure.     This  fresh  blood  is 
still  purer  because  of  the  increased  expansion  of  the  lungs. 

6.  The  Lungs.  —  Gentle  and  slow  exercise  has  little  ef- 
fect upon  the  lungs,  but  rapid  and  vigorous  exercise  expands 
them  till  every  nook  and  cell  is  filled,  and  the  chest   is  de- 
veloped and  enlarged.     A  good-sized  chest  is  very  neces- 
sary to  good  health. 

7.  The  Heart.  — The  heart  is  aided  in  its  work,  as  already 
pointed  out     Long-continued  exercise  puts  more  demands 
upon  the  heart,  which  becomes  strong  with  the  rest  of  the 
muscles.      With  people  who  take  no  exercise,  the  heart 
cannot  be  said  to  become  flabby,  but  it  may  become  weak, 
just  as  any  other  muscle. 

8.  The    Digestive    Organs.  —  Exercise    gives    a    good 
appetite  and  prevents  trouble  in  the  stomach  and  clogging 
of  the  intestines  from  which  lazy  people  are  apt  to  suffer. 

9.  General  Effects.  —  It  promotes  good  humor,  prevents 
vice  and  dissipation,  gives  one  the  agreeable  look  of  health 
and  vigor.     It  is  not  the  pitcher  in  the  baseball  team,  or 


THE  MUSCLES  139 

the  industrious  son,  that  is  most  often  found  loafing  in  a 
back  alley  smoking  cigarettes ;  and  it  is  not  the  industri- 
ous, helpful  daughter  who  is  most  often  found  with  the 
"  blues,"  or  nursing  a  headache. 

235.  Heredity.  —  The  disastrous  effect  upon  the  heart 
of  a  life  of  habitual  muscular  inactivity  is  apparent  in  the 
lives  of  many  people.      The  disappearance  of  dyspepsia 
and  many  other  diseases,  with  the  remarkable  restoration 
to    health   that    follows    judicious    muscular    exercise    or 
physical  labor,  is  likewise  often  seen.     We  have  received 
our  bodies  as  an  inheritance  from  an  ancestry  which  dates 
back  at  least  to  a  time  when  the  human  race   lived   an 
active  life  in  the  open  air.     The  human  body  is  adapted 
to  such  conditions,  and  an  attempt  to  change  these  con- 
ditions too  rapidly,  as  in  the  case  of  city  dwellers,  causes 
extinction.    The  health  and  continuance  of  the  race  under 
conditions  of  city  life  are  aided  by  the  continual  influx  of 
healthy  individuals  from  the  country.     In  a  human  body 
weighing  one  hundred  and  fifty  pounds,  there  are  about 
sixty  pounds  of  muscle,  and  we  cannot  neglect  sixty  pounds 
of  tissue  with  impunity  and  allow  it  to  become  unsound 
from  disuse  (Fig.  126). 

236.  THOUGHT  LESSON.     Position  of  the  Voluntary  Mus- 
cles.—  On   Figs.   125  and   126    mark  the  location  of  the 
muscles    having   the    functions    named   in   the    following 
list.     Locate  them  first  in  your  body  by  performing  the 
action  and  feeling  the  muscle  with  your  hand ;  then  mark 
lightly  with  pencil.     For  instance,  take  question  4 :  locate 
the  muscle  that  bends  the  elbow.     This  is  found  to  be  in 
the  front  of  the  upper  arm,  and  the  figure  "  4  "  placed 
on  the  dotted  line  drawn  from  that  muscle. 

Locate  the  muscle  (or  muscles)  that  — 

1.  Lifts  the  whole  arm  outward  and  upward. 

2.  Draws  it  downward  and  forward. 

3.  Draws  it  downward  and  backward. 


I4O  ELEMENTS   OF  PHYSIOLOGY 

4.  Bends  the  elbow.  10.  Bends  the  knee. 

5.  Straightens  the  elbow*  n.  Straightens  the  knee. 

6.  Bends  the  fingers.  12.  Raises  the  toes. 

7.  Straightens  the  fingers.  13.  Raises    the   body    on 

8.  Turns  the  head  (Fig.  124).  the  toes. 

9.  Draws  the  shoulders  back.  14.  Crosses  the  legs. 

237.  Effect  of  Stimulants  and  Narcotics.  —You  learned 
that   true  fatty  tissue  is  formed  by   the  accumulation  of 
oily  material  within  the  connective  tissue  cells  (Fig.  38). 

238.  The  weaker  forms  of  alcohol,  such  as  ale  and  beer, 
cause  a  change  into  fat  of  much  of  the  albumin  in  muscle 
cells,  thus  bringing  about  a  bloated  and  flabby  condition, 
called  fatty  degeneration.      It  may  even  reach  the  heart, 
causing  a  dangerous  disease  called  Jatty  degeneration  of  the 
heart.     (There  are  other  causes  of  fatty  degeneration.     If 
an  athlete  who  has  developed  enormous  muscles,  suddenly 
ceases   to  train,    his   muscles   may  undergo   fatty  degen- 
eration.)    Through    the  narcotic    or  deadening  effect  of 
alcohol  upon  the  nerves,  they  become  less   sensitive,  and 
fatigue  is  not  so  readily  perceived,  so  the  drinker  has  a 
deceptive  feeling  of  strength  and  power.     It  was  found 
that  two  hours  after  taking  two  ounces  of  whisky  mixed 
with   eight   ounces   of   water,   the    muscular   strength    of 
the  man  experimented  on  was  reduced  one  third.     This 
means  that  a  lifting  power  of  three  hundred  pounds  was 
reduced  to  two  hundred   pounds.     An  old  drunkard  usu- 
ally  has  a  dragging  gait  and  trembling  hands.      Coffee 
sometimes  causes  a  twitching   of  the    eyelids ;   this  is  a 
sign  that  the  body  is  being  poisoned. 

239.  Forms  of  Exercise.  —  It  is  best  to  choose  a  form 
of  exercise  or  labor  which  you  thoroughly  enjoy.      Most 
games  are  excellent  kinds  of  exercise.     Baseball  and  foot- 
ball, played  in  a  sensible  way,  are  admirable.     Such  games 
not  only  strengthen  the  muscles  but  also  develop  presence 
of  mind,  coolness,  fearlessness,  self-control,  and  other  manly 


THE     MUSCLES  141 

qualities.  Men  trained  in  such  sports  may  often  stop 
panics  and  save  lives  in  cases  of  accidents,  or  in  other  emer- 
gencies. Walking,  if  not  done  too  leisurely,  is  fine  exer- 
cise. Americans  probably  make  too  much  use  of  street 
cars.  English  women  are  noted  as  walkers,  going  many 
miles  at  a  time,  and  in  the  cooler  parts  of  the  United 
States,  and  in  cold  weather  in  the  Gulf  states,  this  custom 
would  be  equally  beneficial  in  preventing  nervousness  and 
weakness.  Running  is  a  still  better  exercise,  but  it  should 
be  begun  gradually  and  with  caution,  so  as  to  give  heart 
and  lungs  opportunity  to  become  strong  enough  to  sustain 
the  increased  effort  required  of  them.  One  should  never 
run  with  the  mouth  open  (§  272). 

240.  Boxing  is    fine  exercise    but   should  never  be  in- 
dulged in   with  the   bare    hands.      Two  pairs  of  boxing 
gloves  may  be  said  to  contain  a  whole  gymnasium.     Boxing 
makes  one  sure  and  quick  on  his  feet,  trains  the  eye,  keeps 
the  body  in  an  erect  position,  develops  the  arms,  legs,  and 
back,  and  teaches  control  of  temper.     Wrestling  is  equally 
beneficial,  developing  the  "wind"  and  the  muscles  of  the 
whole  body.     It  should  never  be  practiced  in  the  house, 
unless  in  a  gymnasium,  and  where  there  is  ample  space 
and  no  injurious  objects  to  fall  upon.      Training  in  these 
manly  arts  will  make  one  "  less  likely  to  pay  serious  atten- 
tion to  idle  bluster,  and  less  likely  to  quarrel ;  and  it  may 
prove  valuable  to  know  how  to  defend  oneself  from  the 
attack  of  a  ruffian,  or  bully,  or  drunken  brute,  or  other 
infuriated  animal." 

241.  Cycling   when    properly    done    is   excellent   exer- 
cise, but  the  cycler  that  gets  a  foolish  notion  of  trying  for 
speed  (and  most  of  them  do)  usually  brings  on  the  deform- 
ity of  round  shoulders. 

242.  Dancing,     in     itself,    is     said    to    be    exhilarating 
exercise.      As  usually  conducted,  indoors  instead  of  out- 
doors, prolonged  to  late  hours,  with  overheating,  and  (in 


142 


ELEMENTS   OF  PHYSIOLOGY 


the  case  of  ladies)  sudden  chilling  from  insufficient  clothing 
in  the  region  of  the  chest,  this  exercise  has  serious  draw- 
backs, and  often  wrecks  the  health  of  the  participants. 

243.  Curative   Effects    of    Exercise.  — 
"He  who  does  not  find  time  for  exercise 
must     find    time     for    sickness  "    (Lord 
Derby).    Many  persons  in  declining  health 
have  insisted  on  doing  nothing  but  taking 
the  nauseous  doses  of  patent  medicines, 
or  the  drugs  of  physicians,  but  not  their 
advice,  and  have  died.     But  a  little  change 
in  the  habits  of  life,   such  as  adding  to 
their    usually    sedentary    work     a    little 
gardening,    or    wood-cutting,    or    raising 
flowers,    or   horseback    riding,    or   wood- 
working, or  pedestrian  excursions,  would 
have  restored  them  to  health  and  enabled 
them  to  live  to  a  happy  old  age. 

244.  Exercise    and    Mental    Ability.  - 
Most  men  who  have  been  great  workers 
with  their  minds  have  also  been  zealous 
in  using  their  muscles.     There  is  a  flexi- 
bility of  mind  and  disposition  that  results 
from  a  mixed  occupation  which  is  in  great 
contrast  with  the  machine-like  dullness  and 
narrowness  of  mind  produced  by  a  monoto- 
nous, one-sided  occupation,  whether  men- 

FlG.  127.  —  The  Veins  i        •      i        >-i     i   ^  i  11 

near  the  Surface  on  tal  or  physical.     Gladstone  chopped  down 
trees  ;  Li  Hung  Chang  walked  three  miles 
v"^:  daily,  around  the  courtyards  of  his  palace, 


the  Arm. 


The  fibrous  sheaths  when  eighty  years  old  ;    Napoleon  rode 

covering  most  of  the  . 

muscles  have  not  been  horseback  ;   William  Cullen  Bryant,  upon 

rising  in  the  morning,  swung  a  chair  around 

his  head,  took  wand  exercise  with  a  cane,  and  practiced  other 

gymnastics.     He  walked  five  miles  to  his  work.     Talmage, 


THE  MUSCLES  143 

when  out  for  a  walk  in  the  park,  would  often  run  if  there 
was  no  one  in  sight.  Philip  D.  Armour,  many  times  a 
millionaire,  walked  to  his  office  while  his  clerks  took  the 
street  car. 

245.  Over-development  of  Muscles. — As  important  as 
muscular  exercise  is  for  sending  the  blood  bounding  through 
tha  veins  and  renewing  the  health  of  every  part,  exercise 
can  be  overdone.  Some  athletes  develop  great,  heavy  mus- 
cles which  are  a  burden  to  the  vital  organs  to  support. 
They  do  not  take  care  to  develop  their  lungs  and  breathing 
powers  in  proportion.  Such  athletes  die  young.  Among 
those  who  have  succumbed  to  consumption  may  be  men- 
tioned Kehoe,  the  famous  club  swinger  ;  Dowd,  the  teacher 
of  physical  culture;  "Jap,"  the  wrestler ;  Winship,  the 
inventor  of  the  health  lift ;  Kennedy,  the  strong  man ;  and 
Peter  Jackson,  the  pugilist  (§  238).  Complete  living  with 
conditions  of  health  and  activity  for  all  the  organs,  without 
extreme  use  of  any  of  them,  is  most  conducive  to  a  long 
and  healthful  life. 

PROBLEMS  AND  QUESTIONS  FOR  REVIEW 

1.  In  what  part  of  the  body  are  most  of  the  involuntary  muscles 
situated? 

2.  Name  a  muscle  which  is  wholly  involuntary. 

3.  Can  you  name  any  muscle  which  is  wholly  voluntary  under  all 
circumstances?    To  which  class  do  the  muscles  that  lift  the   eyelids 
belong? 

4.  Which  muscle,  anatomically,  belongs  strictly  to  neither  class? 

5.  If  a  man  had  absolute  control  over  his  muscles  of  respiration, 
what  might  he  do  that  he  cannot  now  do? 

6.  Can  the  muscles  act  independently  of  the  will  in  walking? 

7.  Do  we  shiver  with  the  voluntary  or  involuntary  muscles?     Is 
trembling  usually  involuntary? 

8.  How  many  movable  bones  are  there  in  the  face?     Name  muscles 
attached  to  a  movable  bone  of  the  face. 

9.  What  purpose  do  most  of  the  muscles  of  the  face  serve? 

10.  Why  is  one  who  uses  alcoholic  drinks  not  likely  to  be  a  good 
marksman? 


144  ELEMENTS   OF  PHYSIOLOGY 

11.  Why  should  a  youth  who  wishes  to  excel  in  athletic  contests 
abstain  from  the  use  of  tobacco  ? 

12.  What  order  of  lever  is  the  foot  when  a  weight  is  lifted  on  the 
toes  (Fig.  1 19)  ?     What  order  of  lever  do  we  use  when  we  lift  the  leg 
while  sitting  down  ? 

13.  Locate  the  three  points  of  a  lever  when  swinging  the  arm  from 
the  shoulder ;  when  bending  a  finger ;  when  tapping  the  ground  with 
the  toes  (Fig.  117)  ;  when  using  the  foot  in  walking  (Fig.  118). 

14.  Why  can  we  raise  a  heavier  weight  with  the  hand  when  lifting 
from  the  elbow  than  from  the  shoulder?     (See  Elementary  Physics.) 

15.  Which  bone  is  chiefly  in  motion  when  we  are  using  a  gimlet? 

1 6.  Why  does  using  a  muscle  cause  fatigue  ? 

17.  Why  can  we  chew  harder  with  the  back  teeth  than  the  front 
ones?     (See  Physics.) 

1 8.  Why  is  it  an  advantage  that  the  heel  bone  projects?     That  the 
bones  of  the  limbs  are  enlarged  at  the  joints? 


APPLIED   PHYSIOLOGY 
EXERCISE  I 

1.  Does  a  few  minutes1  practice  in  a  gymnasium  suffice  for  a  day's 
exercise  ? 

2.  Is  there  any  relation  between  the  amount  of  bodily  exertion 
necessary  for  a  person's  health  and  the  amount  of  wealth  he  possesses? 

3.  It  is  said  that  an  Indian  often  runs  or  trots  sixty  miles  per  day, 
and   that  he  rests  his  muscles  without  stopping  by  running  for  a 
while  chiefly  with  the  hip  joint  and  muscles  of  the  thigh,  then  with  the 
knee  joint  and  muscles  of  the  upper  leg.     Can   you  rest  some  of  the 
running  muscles  while  running? 

4.  Can  you  relax  the  chewing  muscles  so  that  the  lower  jaw  will 
swing  loosely  when  the  head  is  shaken? 

5.  Can  you  relax  the  muscles  of  the  forearm  so  that  the  hand  will 
shake  loosely  on  the  wrist  and  the  fingers  in  their  sockets  ? 

6.  Can  you  relax  the  whole  arm  so  that  another  person  can  move  it 
as  a  flexible  rope  ? 

7.  Which  joints  of  the  limbs  lock  and  refuse  to  bend  further  when 
the  limb  is  straightened? 

8.  Which    muscles    have  become   useless  with  most  persons,  al- 
though some  can  still  use  them  (Fig.  122)? 

9.  The  average  man  has  60  Ibs.  of  muscle  and  2  Ibs.  of  brain :  one 
half  of  the  blood  goes  through  the  muscles  and  one  fifth  goes  through 


• 
THE  MUSCLES  1.4.5 

the  brain.     What  inference  may  you  draw  as  to  the  kind  of  life  we 
should  lead? 

10.  What  are  the  beneficial  effects  of  exercise  upon  the  functions  of 
the  skin  ? 

11.  Is  a  slow  formal  walk  suitable  exercise  ? 

EXERCISE  H 

12.  How  can  we  best  prove  that  we  have   admiration  and  respect 
for  our  wonderful  bodies  ? 

13.  What  part  of  the  body  has  the  least  bone  in  proportion  to  the 
other  organs?     In  what  part  of  the  skeleton  is  it  most  important  to 
keep  the  muscular  walls  firm  and  strong  in  order  to  hold  the  internal 
organs  in  position  ? 

14.  Which  of  your  legs  do  you  use  more  than  the  other  in  walking? 
(The  foot  on  that  side  is  larger,  as  shown  by  the  fit  of  the  shoe.)     If 
you  were  lost  on  a  prairie,  to  which  side  would  you  turn  while  trying  to 
go  straight  ? 

15.  How  does  the  fact  that  if  the  nerves  on  one  side  of  the  face  are 
paralyzed  the  face  will  be  drawn  toward  the  other,  illustrate  muscular 
tone? 

1 6.  Why  does  a  game  of  baseball  on  Saturday  afternoon  actually 
rest  a  tired  plow  boy  ? 

17.  What  movements  did  you  ever  see  a  cat  go  through  for  the 
sake  of  exercise  ?  • 

1 8.  What  animals  have  you  ever  seen  play?     Stretch  themselves 
for  exercise? 

19.  Why  do  you  feel  so  exhausted  after  a  fright? 

20.  How  do  you  account  for  the  origin  of  the  mental  state,  which 
holds  in  practice  if  not  in  theory,  that  all  physical  labor  is  an  unmiti- 
gated evil? 

21.  Do  you  know  persons  who  seem  to  be  possessed  by  what  is 
called  "  the  spirit  of  jerkiness  "  ?   How  could  they  overcome  it  (§  227)  ? 

NOTES 

i.  Thought,  Exercise,  and  the  Blood.  —  Professor  Angelo  Mosso  of 
Italy  devised  a  large  balance  on  which  the  human  body  can  be  so  poised 
that  a  change  in  the  distribution  of  blood  can  be  detected  at  once. 
If  the  body  lies  perfectly  balanced  on  the  apparatus,  it  is  evident  that 
an  additional  supply  of  blood  will  cause  the  head  to  sink  if  the  blood 
goes  to  the  head,  or  the  feet  to  go  down  if  the  flow  is  in  the  opposite 
direction.  It  is  found  that  during  study  or  mental  work,  the  head 

L 


146  ELEMENTS   OF  PHYSIOLOGY 

sinks  in  a  very  short  time.  Students  balanced  before  and  after  written 
examinations,  showed  that  the  center  of  gravity  had  risen  from  ^  inch 
to  2 \  inches.  W.  G.  Anderson,  director  of  the  Yale  Gymnasium, 
found  that  mere  thought  will  send  a  supply  of  blood  to  parts  of  the 
body.  A  man  perfectly  balanced  will  find  his  feet  sinking  if  he  goes 
through  leg  gymnastics  mentally  but  does  not  make  the  movements. 
The  flow  of  blood  to  an  exercised  part  is  affected  by  the  attitude  of  mind 
of  the  person  exercising.  If  a  man  exercises  in  a  listless,  mechanical 
manner,  the  center  of  gravity  is  not  changed  to  any  extent ;  but  when 
a  man  takes  a  series  of  movements  in  a  conscious  and  highly  volitional 
manner,  the  increase  in  the  supply  of  blood  to  the  arms  or  legs,  accord- 
ing to  the  movements  taken,  is  very  noticeable.  If  two  men  exercise 
the  arms  and  thorax,  one  standing  before  a  looking-glass,  the  other  not, 
the  former  will  show  a  greater  rise  of  the  center  of  gravity  than  the 
other,  or  a  richer  supply  of  blood  to  the  parts.  The  looking-glass  aids 
him  in  concentrating  his  mind  on  the  parts  exercised.  Dr.  Anderson 
also  finds  that  movements  in  which  men  take  pleasure  send  blood  more 
abundantly  to  parts  than  do  movements  which  are  not  to  their  liking. 
These  experiments  furnish  important  conclusions  as  to  the  manner  of 
taking  exercise,  and  the  kind  of  exercise  to  be  taken  in  order  to  obtain 
the  greatest  benefit  therefrom. 

2.  Unfortunately,  the  majority  of  human  beings  regard  the  necessity 
of  sweating  as  a  calamity ;  and  to  dodge  sweating,  to  earn  one's  liveli- 
hood in  some  other  way,  seems  to  be  the  special  aim  of  a  growing 
multitude  in  all  civilized  lands.     But  sweating  is  a  blessing  in  disguise. 
The  Scripture  maxim  teaches  us  that  if  any  will  not  work,  neither  shall 
he  eat,  —  either  from  poverty  or  indigestion.     Nature  tells  us,  "  They 
who  will  not  earn  an  appetite,  cannot  digest,"  and  further  she  says  with 
equal  emphasis,  "  He  that  will  not  work  shall  not  sleep1'  (J.  H.  Kellogg). 

3.  Effect    of    Exercise    on    Growth.  —  Henry    G.    Beyer,   M.D., 
reported  observations  on  the  growth  of  188  naval  cadets  who  took 
special  systematic  exercise,  and  compared  it  with  the  usual  growth  of 
cadets  of  the  same  age. 

There  was  an  increase  in  height  of  more  than  one  inch  above  that 
which  took  place  without  the  special  exercise. 

The  increase  in  strength  was  five  times  as  much  as  the  normal 
increase. 

There  was  an  increase  in  weight  of  77  pounds  in  the  four  years  during 
which  the  observations  were  made. 

There  was  an  increase  in  lung  capacity  of  1.72  liters. 


PART    III.      HOW    THE    BODY    IS 
NOURISHED 

CHAPTER  X 

THE   RESPIRATION 

246.  Why  Breathing  Organs  are  needed.  —  Every  cell  in 
the  body  requires  oxygen  to  enable  it  to  do  its  appointed 
work.     When  the  supply  of  oxygen  stops,  the  activity  of 
the  cell  ceases  at  once.     If  it  is  a  muscle  cell,  motion  can 
be  generated  in  the  muscle  only  by  the  union  of  oxygen 
with  the  contents  of  the  cell.     If  it  is  a  gland  cell,  it  can- 
not do  its  work  of  secreting  useful  fluids  without  the  help 
of  oxygen,  for  the  substances  which  the  gland  cell  takes 
from  the  blood  must  be  changed  to  form  the  secretion.     If 
the  cell  is  a  brain  cell,  although  it  may  not  use  as  much  as 
a  muscle  cell  uses,  oxygen  is  still  indispensable.     The  oxi- 
dation that  takes  place  in  the  various  cells  results  in  the 
formation  of  carbon  dioxid  and  other  waste  products  which 
would  destroy  the  life  of  the  cell  if  allowed  to  remain ; 
these  are  removed  from  the  body  by  the  same  organs  that 
supply  the  oxygen. 

247.  What  must  be  the  Nature  and  Structure  of  a  Breath- 
ing Organ?  —  It  is  obvious   that  in  animals  of  large  size 
with  many  tissues,  the  great  majority  of  the  living  cells  of 
the  tissues  must  be  buried  deep  away  from  the  external 
surface.     But  even  if  deep-seated  and  away  from  the  air, 
the  living  cells  have  the  same  need  of  oxygen  as  though 


148  £L£M£NTS   OF  PHYSIOLOGY 

near  the  surface.  If  oxygen  is  supplied  to  the  blood,  the 
latter  conveys  the  oxygen  to  the  cells;  but  it  is  seen  that  a 
very  efficient  organ  is  needed  to  supply  the  blood  with  oxy- 
gen sufficient  for  so  many  cells.  The  breathing  apparatus 
varies  in  different  animals ;  it  usually  consists  of  a  device 
for  exposing  to  the  air  a  great  amount  of  thin  tissue,  which 
is  a  specialized  form  of  the  outer  skin  of  the  animal  (if 
the  animal  is  not  a  land  animal,  the  tissue  is  exposed  to 
the  water) ;  the  animal  is  further  provided  with  means  to 
keep  up  a  current  of  air  (or  water)  on  the  outside  of  this 
modified  skin  and  a  current  of  blood  on  the  inside.  In 
some  small  animals,  as  the  ameba  and  the  earthworm,  the 
simple  external  body  surface  is  sufficient  for  the  purpose 
of  breathing.  But  large  animals  with  many  deep-seated 
and  inaccessible  cells  require  an  increase  of  surface,  which 
is  supplied  by  having  the  oxygen-absorbing  surface  inside 
of  the  body  and  by  having  it  folded  or  provided  with  tubes 
or  branches  of  the  greatest  degree  of  complexity.  In  man, 
it  has  been  estimated  that  by  the  finer  and  finer  division  of 
the  air  sac,  a  pair  of  human  lungs  presents  to  the  air  a 
surface  of  at  least  one  hundred  square  feet  (or  ten  feet 
square).  The  remainder  of  the  breathing  apparatus'  con- 
sists of  muscles  for  changing  the  air  that  is  in  contact 
with  this  great  surface. 

248.  Definitions.  — The  passing  of  the  air  into  the  lungs 
is  called  inspiration,  and  the  passing   of  the  air  out  from 
the  lungs  is  called  expiration.     The  two  together  constitute 
respiration,  or  breathing. 

249.  Anatomy    of    the    Respiratory   Organs.  —  The   air 
usually  passes  in  at  the  nose  and  returns  by  the  same 
way,  except  during  talking  or  singing.     If  you  look  in 
your  mouth  with  a  mirror,  you  will  see  at  the  back  part 
an   arch  which  is  the  rear  boundary  line  of  the  mouth. 
Just  above  the  arch  is  likewise  the  limit  for  the  back  part 
of  the  nasal  passages.     The  funnel-shaped  cavity  beyond, 


THE  RESPIRATION 


149 


into  which  both  the  mouth  and  nasal  passages  open,  is 
called  \h.Q  pharynx  (far1  inks),  or  throat.  Below,  two  tubes 
open  from  the  pharynx,  one  into  the  trachea  (trdk'e-a) 
or  windpipe,  the  other  into  the  esophagus,  or  gullet.  At 
the  top  of  the  trachea 
(Fig.  129)13  the  carti- 
laginous larynx,  or 
voice  box,  and  the 
opening  from  the 
throat  is  provided 
with  a  lid,  the  epi- 
glottis, also  consisting 
of  cartilage.  The  lar- 
ynx will  be  described 
more  fully  in  treating 
of  the  voice ;  it  may 
be  felt  as  the  Adam's 
apple.  Just  below  it 
comes  the  trachea 
proper  which  is  a  tube 
about  three  fourths  of  FIG.  128. 

an    inch    in    diameter,      I;  largest  cartilage  of  larynx;    »,   lowest  cartilage  of 

and  about  four  inches  %£&££*"*  the  divisions  and  subdivision$ 
long  (Fig.  129).  It 

consists  of  hoops  of  cartilage  which  are  not  complete 
circles  but  are  shaped  somewhat  like  the  letter  C,  being 
completed  behind  by  nonstriated  (involuntary)  muscular 
tissue  (Fig.  130),  whose  function  is  to  draw  the  ends 
of  the  rings  together  at  times,  e.g.  during  coughing, 
and  reduce  the  caliber  of  the  tube.  The  function  of 
the  hoops  of  cartilage  is  to  keep  the  windpipe  open 
at  all  times.  If  it  should  collapse  under  pressure,  life 
might  be  lost.  These  rings  of  cartilage  may  be  felt  in 
the  neck. 

250.   The  lower  end  of  the  trachea  is  just  behind  the 


ISO 


ELEMENTS   OF  PHYSIOLOGY 


upper  end  of  the  sternum ;  and  there  it  divides  into  two 
bronchi,  called  the  right  bronchus  and  the  left  bronchus 
(plural,  bronchi}  (Fig.  129).  The  bronchi  subdivide  into  a 
greatnumberof  smaller 
branches,  called  bron- 
chial tubes.  Cartilage 
is  found  in  the  walls  of 
all  but  the  smallest  of 
the  tubes.  The  subdi- 
vision continues  until 
the  whole  lung  is  pene- 
trated by  branches,  all 
having  the  general 
name  of  bronchial 
tubes  (Fig.  128).  The 
smallest  are  only  about 
y1^-  of  an  inch  in  di- 
ameter. They  ramify 
through  the  lungs, 
somewhat  like  the 
branching  of  a  tree, 


FlG.  129.  —  The 
chea  (front) . 

h,  hyoid  bone;  /,  tf,  thy-     "         "*&  *     a>  arytenoid  cartilages;   h, 

cartilage;    c,   cri-     f Unnel-Shaped  Chamber         hyoid   bone;    *,  t',   thy- 


Tra-  each  tiny  tube   finally  FlG-    130. -The   Tra- 

..  .  .,v  chea  (back). 

ending     in     a     wider 


coid;  e,  epiglottis;  tr,  777       /T— 

trachea;      b     and     b',    Called      3.      lOOUle     (Fig. 
bronchi. 


roid  cartilage;  c,  cricoid, 
<?,  epiglottis;  tr,  trachea; 
b  and  b1,  bronchi. 


131),  into  which  so 
many  dilated  sacs,  called  air  cells,  open  that  the  walls  of 
the  terminal  chamber,  or  lobule,  may  be  said  to  consist  of 
tiny  cups,  or  air  cells,  placed  side  by  side.  (The  word 
"  cell "  is  here  used  in  its  original  sense  to  denote  a 
cavity  or  chamber,  and  not  in  the  sense  of  a  protoplasmic 
cell.) 

251.  The  wall  of  an  air  cell  consists  of  elastic  connective 
tissue  lined  with  a  layer  of  very  flat  and  thin  epithelial  cells 
(Fig.  132).  This  lining  is  continuous  with  the  epithelial 


THE  RESPIRATION 


lining  of  the  bronchial  tubes.     It  is  so  thin  as  to  offer  almost 
no  obstruction  to  the  passage  of  oxygen  out  of  the  cell  and 
the  entrance  of  the  carbon  dioxid  from 
the  blood  vessel  (Fig.  133). 

252.    Ciliated  Cells. —  It  must  be  re- 
membered that  mucous  membrane  lines 
all  cavities  in  the  body  accessible  to  the 
air.  Almost  all  of  the  nose  and  pharynx, 
and  all  of  the  air  passages  as  far  as  the 
lobules,  are  lined  with  a  mucous  mem- 
brane the  cells  of  which  are  furnished 
with  cilia  (Fig.  134).    These  are  minute 
FIG.  131.— TWO  Lobules  at  hair  like  filaments  which  are  in  constant 
the  End  of  a  Bronchial  motion.     When  a  few  of  the  cells  are 

Tube.  . 

examined  under  a  microscope,  we  may 
see  the  cilia  in  motion,  even  for  a  time  after  the  removal  of 
the  cells  from  the  body.  They  make  a  quick  stroke  up- 
ward, and  move  back  more  slowly,  and  this  is  found  to 
give  them  the  power  of  moving  particles  of  dust  which 
enter  the  lungs  upward  toward 
the  larynx.  Upon  reaching  the 
larynx,  the  dust  brings  about  irri- 
tation which  causes  it  to  be  coughed 
up.  In  the  nasal  passages,  they 
serve  a  similar  purpose.  At  the 
opening  of  the  nostrils  are  also 
placed  ordinary  hairs  (hundreds  of 
times  larger  than  cilia),  which  aid 
in  cleaning  the  air  of  dust  as  it 
enters  the  nose. 

253.  The  Blood  Tubes  in  the  Lungs.  —  Near  where  the 
trachea  divides  into  the  two  bronchi,  the  pulmonary  artery, 
bringing  the  dark  blood  to  the  lungs,  divides  into  two 
branches,  and  the  subdivision  continues,  until,  finally,  a  net- 
work of  capillaries  is  formed  around  each  lobule,  or  cluster 


FIG.  132.  — The  Wall  of  an  Air 
Cell. 

*,  the  epithelium;  t,  partition  be- 

tween  two  air  cells,  in  which  the 
capillaries  lie;    c,  fibers  of  elastic 

tissue> 


152 


ELEMENTS   OF  PHYSIOLOGY 


a,  network    of   capillaries;    bt 
small  arteries  and  veins. 


of  air  cells.     These  capillaries  are  the  termination  of  the 

branches  of  the  pulmonary  artery,  and  the  beginning  of  the 

pulmonary  veins.     It  is  here  that  the 

blood  changes  from  a  purplish  red  to 

a  rosy  red.     A  fine  connective  tissue 

holds  together  all  these  air  cells  and 

tubes. 

254.    The  Lungs  Entire.  —  The  en- 
tire cavity  of  the  chest   except   the 

space  occupied  by  the  heart  and  a  few 

of  its  blood  vessels  and  the  esophagus,    FlG  I33._The  Blood  Ves. 

is  filled  by  the  lungs  and  their  cover-    seis  around  TWO  Air  Ceils. 

ings.   The  lungs  are  light  pink  in  early 

life  but  become  grayish  and  darker 

as  age  advances.     This  change  is  more  marked  in  persons 

who  dwell  in  large  cities  or  where  the  atmosphere  is  smoky 

and  dusty.  The  lungs,  or  a  part 
of  one,  will  float  if  thrown  upon 
water.  The  right  lung  has  three 
lobes,  or  divisions,  and  the  left, 
two  lobes.  The  lower  end,  or 
apex,  of  the  heart  hangs  some- 
what to  the  left,  diminishing  the 
space  for  the  left  lung.  The 
general  substance  of  the  lungs 
consists  of  bronchial  tubes,  blood 
vessels,  lymphatics,  and  air  cells, 
as  above  described,  the  air  cells 
being  chiefly  near  the  surface. 

FIG.  i34.— ciliated  Ceils  from  the       255.  The    Pleuras.  —  The   sur- 

Trachea    of   a    Rabbit,    highly 

magnified.  face  of  the  lungs  is  not  in  con- 

m,  m,  mt  mucous  ceils  in  various  tact  with  the  chest  wall.     Imagine 

stages  of  secreting  mucus.  ,          c    ..  . 

a  closed  bag  or  sac  made  of  thin 

membrane  lining  the  whole  of  the  chest.     Now  imagine 
another  closed  sac  a  little  smaller,  that  is  inside  of,  and 


THE  RESPIRATION  153 

lining,  the  first  one.  Next  imagine  the  lungs  to  be  found 
inside  the  inner  sac.  Here  we  have  the  lungs  within  the 
two  membranes,  called  the  plenras.  The  heart  is  in  the 
chest,  but  is  not  inclosed  by  the  pleuras.  It  is  in  a  deep 
indentation  in  the  lower  surface,  such  as  you  might  make 
in  a  paper  bag  by  pressing  your  fist  up  into  the  bottom 
without  breaking  the  bag. 


FIG.  135.  —  The  Dome-shaped  Diaphragm. 

A,  aorta;  B,  esophagus;  C,  vena  cava  inferior;  Z>,  muscular  pillars  of  the  diaphragm 
arising  from  the  spinal  column  E;  F,  ribs,  and  G,  sternum,  sawed  through  so  as  to  allow 
removal  of  the  front  of  the  thorax ;  H,  hind,  and  Kt  front,  muscular  sheet,  and  /,  central 
tendinous  part  of  diaphragm. 

256.  Use  of  the  Pleuras. — The  outer  pleura  lines  the 
chest  wall,  the  inner  pleura  covers  the  lungs.  The  two 
membranes  form  between  them  a  closed  sac,  a  serous  cavity 
which  is  air-tight  and  aids  the  lungs  in  following  the  chest 
wall  without  friction  when  the  chest  expands.  The  two 
pleural  surfaces  are  in  contact,  and  secrete  just  enough 
fluid  to  enable  them  to  glide  smoothly  upon  each  other. 


154 


ELEMENTS   OF  PHYSIOLOGY 


But  for  the  pleura  there  would  be  friction  between  the 
lungs  and  the  chest  walls. 

257.  The    Diaphragm   (Fig.    135). —The   floor   of   the 
chest  cavity  is  formed  by  a  muscle  that  is  the  broadest  in 
the  body,  and  also  the  thinnest  in  proportion  to  its  width. 
It  is  called  the  diaphragm.     It  rounds  up  under  the  concave 
base  of  the  lungs  somewhat  like  a  dome  and  separates  the 
thoracic  and  abdominal  cavities.     It  is  attached  to  the  low- 
est ribs  at  the  sides  and  to  the  lumbar  vertebrae  behind 
(Fig.  135).     Its  rounded  side  is  turned  toward  the  chest,  and 
its  hollow  side  toward  the  abdomen.     It  is  the  most  im- 
portant muscle  of  the  respiratory  system.    When  it  contracts, 
it  flattens  and  descends,  and  the  lungs  descend  with  it,  thus 

lengthening  and  enlarging  the 
cavity  of  the  chest  from  top  to 
bottom. 

When  the  diaphragm  de- 
scends, it  acts  as  a  piston  or  a 
tight-fitting  round  board  would 
act  if  pressed  down  into  a  barrel 
of  water.  If  there  were  two 
holes  in  the  board  (correspond- 
ing to  the  vena  cava  and  the 
thoracic  duct),  the  water  would 
be  pressed  up.  Thus  the  circula- 
FIG.  136.— Figure  showing  Three  tion  is  aided  by  breathing.  When 

2M±£-Tia£  the  diaPhrasra  relaxes> its  thin- 

completing  the  Thoracic  Wail.       ness  and  flexibility  would  allow 

A,  sternum;  B,  rib  cartilage;  C,  verte-     ft   fa   drOD    downward,  instead   of 
bral  column;  F,  rib;    G,  outer  inter- 
costal muscles;    H,  inner  intercostal     Springing  Upward  as  pupils  SOmC- 

times  suppose ;  but  the  abdomi- 
nal walls  contract  as  the  diaphragm  relaxes  and  force  the 
liver,  stomach,  etc.,  against  the  diaphragm,  thus  pressing  it 
against  the  lungs  (Figs.  137  and  138). 

258.  Other  Muscles  that  expand  the  Chest.  —The  chest 


—A 


G' 


THE  RESPIRATION 


155 


walls  can  also  be  lifted  out  at  the  sides  and  in  front.  This 
is  accomplished  by  muscles  leading  from  the  shoulders  and 
spinal  column  to  the  outer  surface  of  the  ribs  (Fig.  124), 
and  by  the  intercostal  muscles,  or  the  muscles  that  connect 
each  rib  with  the  rib  above  (Figs.  136,  140).  Thus  the 
chest  may  be  made  deeper  from  front  to  back  and  from 
side  to  side,  and  if  the  diaphragm  acts  at  the  same  time,  the 
chest  is  elongated  from  top  to  bottom,  and  thus  is  enlarged 
in  all  directions. 


FlGS.  137  and  138.  —  Diagrams  to  show  the  Positions  in  Respiration  of  the  Ster- 
num, Diaphragm,  and  Abdominal  Wall. 
A,  inspiration;    3,  expiration;    Tr,  trachea;    St,  sternum;  D,  diaphragm;  Ab,  abdominal 

wall.     The  shaded  part  is  to  indicate  the  stationary  air.     The  unshaded  part  shows  the 

increased  air  space  during  inspiration. 

259.  Inspiration. — The  lungs  themselves  contain  no 
muscular  tissue ;  therefore  they  cannot  expand  by  any 
force  of  their  own.  Yet  they  expand  when  the  chest  ex- 
pands. How  does  the  enlargement  of  the  chest  cause  the 


156 


ELEMENTS   OF  PHYSIOLOGY 


lungs  to  expand,  and  the  air  to  rush  in  ?  The  air  cannot 
be  pulled  in,  for  it  has  no  cohesion,  its  parts  do  not  stick 
together.  It  is  found  that  the  air  has  considerable  weight, 
for  the  height  of  the  atmosphere  is  at  least  forty  miles,  and 
the  air  above  is  pressing  down  on  that  below.  When  the 

chest  walls  are  moved  outward 
against  the  weight  of  the  outer 
air,  the  space  in  the  chest  is  in- 
creased, and  the  air  already  in  the 
chest  expands  to  fill  the  greater 
space.  The  air,  when  expanded, 
is  lighter,  and  exerts  less  pressure 
than  before,  and  the  denser  air 
outside,  having  greater  pressure, 
presses  inward  until  the  air  in  the 
lungs  is  as  dense  as  it  was  before 
the  lungs  were  enlarged.  Thus 
do  we  allow  the  air  to  come  into 
our  lungs  ;  we  do  not  draw  it  in, 
but  make  space  for  it,  and  the  at- 
F,G.  ,39.  -Diagram  of  riand  "osphere  outside  presses  it  in. 

260.     Expiration.  —  This   is    the 

reverse  of  inspiration.    The  space 

within  the  chest  is  diminished,  and 

^  ^  jn  ^  }  {&  CQm  ed 

and  becomes  denser  than  the  air 
outside.  This  denser  air  has 
greater  pressure  than  the  outside  air,  and  presses  out 
through  the  air  passages  until  enough  has  passed  out  to 
restore  the  equilibrium,  making  the  pressure  equal  without 
and  within  (Figs.  137,  139). 

261.  But  how  are  the  Lungs  made  Smaller  ?  In  ordinary 
quiet  breathing,  the  lungs  become  smaller,  owing  chiefly  to 
the  elasticity  of  the  parts  involved.  When  the  air  rushes 
in  during  inspiration,  it  enlarges  the  air  cells  by  stretching 


Seventh    Ribs,   in   Connection 


tion    the    Latter    is    carried 

upwards  and  forwards. 
The   expiratory  position  is  indicated 

by  continuous  lines,  the  inspiratory 


THE  RESPIRATION 


157 


their  walls,  and  the  walls  being  made  partly  of  elastic  tis- 
sue, the  cells  contract  again  when  the  muscles  of  inspiration 
cease  to  act.  When  the  ribs  are  lifted  up  during  inspira- 

tion, the  costal  cartilages 
that  connect  them  with 
the  sternum  are  slightly 
bent,  and  the  elasticity 
of  these  cartilages,  as 
well  as  the  weight  of  the 
chest  wall,  causes  the 
ribs  to  become  lower 
when  the  muscles  of 
inspiration  cease  to  act. 

Many  DUDils  £T6t  the   QT- 
" 

TOnCOUS      idea      that      the 


Diagram  to  show  action  of  intercostal  muscles.  At 
A  two  ribs  are  represented  in  passive  position.  If 
line  ac  shortens,  the  ribs  will  go  down  as  in  B. 

If  line  bd  shortens,  the  ribs  will  rise  as  in  C.    One      .  .        ,  . 

line  represents  an  inner,  and  the  other  an  outer,     diaphragm    IS    alSO 
intercostal  muscle.    A  frame  made  with  jointed  cor- 
ners  (with  strings  to   represent  the  muscles)  will 


4.*  J 

tlC    aild 


j 
Upward 


readily  demonstrate  the  action  of  the  two  layers  of    When  it  relaXCS,  thus  aid- 
intercostal  muscles. 

ing   expiration.      When 

relaxed,  it  has  no  more  elasticity  than  a  piece  of  cloth, 
and  no  more  power  to  push  itself  upward.  However, 
the  abdomen  has  been  somewhat  compressed,  and  its  walls 
somewhat  stretched  during  the  inspiration.  When  the 
diaphragm  relaxes,  the  elasticity  of  the  muscular  walls  of 
the  abdomen  presses  the  organs  against  the  under  side 
of  the  diaphragm,  pressing  that  in  turn  against  the  base 
of  the  lungs,  and  aiding  expiration. 

262.  Quiet  or  Passive  Expiration  is,  therefore,  a  rebound 
brought  about  by  the  elasticity  of  the  air  cells,  costal 
cartilages,  and  abdomen,  and  by  the  weight  of  the  chest 
wall.  Active  expiration  adds  muscular  contraction  to  the 
above  forces.  The  two  layers  of  intercostal  muscles  are 
among  those  used  in  inspiration  and  active  expiration 
(Figs.  136,  140).  The  outer  muscles  diminish  the  spaces 
between  the  ribs  when  they  contract,  and  thus  move  the 


158 


ELEMENTS  OF  PHYSIOLOGY 


ribs  upward  and  outward  (Fig.  140).  (Place  the  hands  at 
the  sides  of  the  waist  while  inspiring,  and  this  will  be 
noticed.)  The  inner  muscles  increase  these  spaces  when 
they  contract,  and  thus  depress  the  ribs  and  aid  in  expira- 
tion (Fig.  137).  In  active  expiration  the  abdominal  walls 
contract  and  press  the  abdominal  organs  against  the  dia- 
phragm. By  feeling  the  body,  find  the  location  of  the 
muscles  that  contract  during  strong  expiration.  Feel  the 
same  muscles  during  the  act  of  coughing. 

263.  THOUGHT  LESSON.  Ease  in  Breathing.  —  By  study- 
ing the  skeleton  of  the  chest  (Figs.  59,  141),  carefully 
observing  the  bones  and  cartilages,  and  by  experimenting 
upon  his  or  her  own  breathing,  the  pupil  is  to  fill  out  the 
following  reasons  why  expansion  and  contraction  of  the 
lower  chest  ("waist  breathing")  is  easier  than  breathing 
with  the  upper  chest  ("  collar-bone  breathing  "). 

1.  There   are  two   pairs  of 

ribs   below,   while   there   are   none 
above. 

2.  There  are  three  pairs  of 

ribs   below,  while   there   are    none 
above,  but  all  the  ribs  of  the  upper 
chest  are ribs. 

3.  The  joints  between  the  seven 
pairs  of  true  ribs  and  the  sternum 

are  more  flexible  below  because . 

(Observe  carefully  Figure  141.) 

4.  In  waist  breathing  the  breaths 

will  not  have  to  be  so  frequent  to  supply  the  same  amount 
of  air,  because  the  lower  chest,  besides  being  more  flex- 
ible, is  than  the  upper  chest. 

5.  The  walls  of  the  waist  swing  -     -  and while  the 

walls  of  the  upper  chest  must  move  -    -  and  -  — . 

6.  The  bones  of  the  —  —  rest  upon  the   upper  chest. 
In  upper  chest  breathing  their  weight,  and  the  weight  of 


FIG.  141. 


THE  RESPIRATION  159 

both   of  the  -    — ,  must,   therefore,   be   lifted.     (Test  by 
experiment.) 

264.  Modifications  of  the   Breath.  —  After  studying  the 
following  list  and  experimenting  with  your  own  breathing, 
write  after  each  word,  I  or  E,  according  as  inspiration  or 
expiration  is  chiefly  involved  in  the  action.     Study  each 
action  in  other  respects  also :  — 

Sighing  Coughing  Sneezing 

Sobbing  Laughing  Hiccoughing 

Crying  (of  a  child)  Yawning  Snoring 

265.  Air  is  composed  of  a  mixture  made  up  chiefly  of 
oxygen,  nitrogen  and  a  very    small   quantity   of    carbon 
dioxid.     Nitrogen  is  colorless,  tasteless,  and  odorless ;   it 
does    not  support   combustion,  and    is   one  of  the   most 
inactive  gases  known  to  chemists.       The  oxygen   of  the 
air  is  also  colorless,    tasteless,    and   odorless,  but   is  one 
of  the  most  active  gases  known  to  chemists.       The  air 
exhaled  contains   about  the  same  amount  of  nitrogen  as 
that  inhaled,  but  it  contains  much  less  of  oxygen,  the  latter 
having  been  replaced  by  an  almost  equal  quantity  of  carbon 
dioxid. 

266.  One  Hundred  Parts  of  Pure  Air  contain  about  20 
parts  of  oxygen,  nearly  80  parts  of  nitrogen  ( and  other 
gases),  and  .004  of  a  part  of  carbon  dioxid.      Air  com- 
ing from  the  lungs  contains   16  parts  of  oxygen,  nearly 
80  parts  of  nitrogen,  and  over  4  parts  of  carbon  dioxid. 
The  air  while  in  the  lungs  has  lost  four  parts  of  its  oxygen, 
there  has  been  no  change  in  the  quantity  of  nitrogen,  and 
it  has  gained  four  parts  of  carbon  dioxid.       The  oxygen  is 
in  the  air  in  order  to  supply  an  element  to  animals  essential 
to  their  activity.     The  nitrogen  in  the  air  is  not  used  in  the 
body.      The  small  amount  of  carbon  dioxid  in  the  air  sup- 
plies the  plants  with  carbon.    Its  quantity  is  being  constantly 
added  to  by  fires  and  by  the  breath  of  animals.     The  leaves 


160  ELEMENTS   OF  PHYSIOLOGY 

of  plants,  aided  by  the  sunlight,  are  constantly  removing 
it,  so  that  it  is  kept  at  .004  of  one  per  cent  in  the  air.  If 
it  increases  in  the  blood  greatly  beyond  the  usual  amount, 
dullness  of  mind  and  finally  unconsciousness  result. 

267.  Foul   Air.  —  Besides   the    carbon   dioxid,    the    air 
coming  from  the  lungs  contains  a  small  and  variable  quantity 
of  water  and  of  foul-smelling  vapors.     In  the  air  of  a  closed 
room  in  which  several  persons  have  been  for  some  time, 
there  is  a  characteristic  odor  which  belongs  to  man,  just  as 
there  are  odors  peculiar  to  each  of  the  lower  animals.     The 
odors  are  caused  by  fine  organic  particles  from  the  skin 
and  lungs  of  the  persons.      When  a  number   of  human 
beings  are  together,  and  the  ventilation  is  imperfect,  the 
air  becomes  very  oppressive  and  is  called  "  crowd  poison." 
Although  it  is  given  off  by  the  cleanliest  and  healthiest 
persons,  the  "  crowd  poison  "  accumulates  faster  if  indi- 
viduals in  the  room  (  whether  it  be  church,  school,  parlor, 
or  theater )  have  catarrh,  decayed  teeth,   or  some   other 
diseased  condition.      The  necessity  for  breathing  and  ven- 
tilation is  just  as  great,  because  of  these  organic  particles, 
as  it  is  for  the  purpose  of  preserving  the  proper  propor- 
tion of  inorganic  elements  in  the  air.      Headaches  and 
other  symptoms  of  distress,  caused  by  ill-ventilated  rooms, 
are  to  be  attributed  chiefly  to  the  effects  of  the  "  crowd 
poison  "  upon  the  nerves. 

268.  THOUGHT    LESSON.     Protective    Instincts:    Effects 
of  Tobacco  on  Lungs  and   Habits   of  Life.  —  i .  Chemical 
analysis  shows  that  there  is  enough  nicotine  in  one  cigar 
if  taken  into  the  system,  to  kill  two  men.     Does  the  expe- 
rience of  tobacco  users  disprove  this  ? 

2.  Name,  in  four  words,  four  disagreeable  effects  that 
soon  follow  smoking  a  pipe  or  strong  cigar  for  the  first 
time. 

3.  Name  two  qualities  belonging  to  tobacco  that  God 
has  given  it  in  order  to  teach  us  through  the  senses  that 


THE  RESPIRATION 


161 


it  is   not   good   for   us   and   that  we   should   not  try   to 
use  it. 

4.  What  change  does  God  cause  to  come  over  our  in- 
stinct to  avoid  harmful  things  if  we  disregard  the  warnings 
as  if  they  were  from  an  unwise  source  ? 

5.  What  means  have  shrewd  manufacturers  provided  so 
that  even  children  now  learn  to  smoke  so  gradually  as  not 
to   awaken   the   instinctive  repugnance  to  the  poison  in 
tobacco  ?     What  aids  in  learning  to  chew  tobacco  ? 

6.  What  injury  results  from  chewing  tobacco  that  does 
not  result  from  smoking  ?     What  injury  results  from  smok- 
ing that  does  not  result  from  chewing  (§  284)? 

7.  Where  has  the  smoke  been  that  a  boy  blows  out  of 
his  nose  ?     What  does  such  a  boy  usually  smoke  ? 

8.  Give  several  reasons  why  weak  tobacco  smoke  in  the 
lungs  does  a  far  greater  amount  of  injury  than   strong 
tobacco  smoke  in  the  mouth. 

9.  Why  do  cigarette  smokers  usually  inhale,  or  draw 
the  smoke  into  the  lungs,  while  cigar  smokers  do  not  ? 

10.  Think  of  three  boys  (without  writing  their  names) 
whom  you  know  that  do  not  use  tobacco,  and  of  three  that 
smoke  cigarettes  habitually.  Fill  out  the  following  table, 
placing  the  boys  in  two  classes,  and  showing  how  many 
of  the  three  tobacco  users  are  fleshy,  and  how  many 
are  thin,  etc.  ;  how  many  of  the  three  abstainers  are 
fleshy,  how  many  of  the  three  are  thin,  etc. 


I 

£ 

M 

Pale  or 
sallow. 

Studious. 

1 

Obedient. 

>, 

| 
& 

Full  sized. 

Stunted. 

3  tobacco  users, 

3  abstainers, 

1 62  ELEMENTS   OF  PHYSIOLOGY 

269.  Subjects  for  Compositions.  —  The  Benefits  and  Dis- 
advantages of  Bicycling.  Natural  and  Artificial  Beauty. 
My  Personal  Observations  and  Experiences  in  the  Light 
of  Physiology.  Natural  Cures  and  Medicines.  The 
Breath.  Tobacco.  Alcohol  and  Crime.  Tight  Shoes. 
Sketch  of  the  Life  of  a  Friend.  Exercise.  The  Lungs. 
The  Cigarette  Habit.  Health  and  Happiness. 


CHAPTER  XI 
HYGIENE  OF  RESPIRATION 

270.  Dust.  —  The  cilia  of  the  air  passages  stop  most  of 
the  dust  before  it  reaches  the  lungs,  but  not  all.     If  the 
dust  is  excessive,  millions  of  particles  enter  the  lungs.     If 
a  housekeeper  would  examine  the  air  of  the  room  with  a 
beam  of  light  reflected  by  a  mirror  during  the  time  of 
sweeping,  she  would  often  be  horrified,  and  would  heed 
the  caution  of  those  who  say  that  every  door  and  window 
should  be  opened  before  beginning  to  sweep,  and  allowed 
to   stay  open  for  two    hours    afterward.      If   there   is   a 
breeze,    so    much    the    better ;    it    blows    the    dust    out, 
especially  if  she  sweeps  in  the  direction  of  the  breeze.     It 
is  the  presence   of   dust  floating  in  the   air,    more   than 
fragments  of   trash  upon  the  floor,  that   makes   a   dirty 
home. 

271.  When  a  carpet  is  swept,  dust  comes  from  the  carpet 
itself,  especially  if  it  is  old.     Curtains  and  hangings  also 
hold  dust.     Hardwood  floors,  with  rugs  instead  of  carpets, 
are   recommended,    and    oilcloth    and    linoleum    are   also 
excellent  substitutes  for  carpets.     Rugs  can  be  conveniently 
cleaned  at  any  time,  and  the  floor  can  be  cleansed  with  a 
moist  cloth.     Statistics  indicate  that  among  civilized  races 
a  large  proportion  of  the  deaths  is  due  to  lung  diseases. 
This  proportion  is  frequently  estimated  as  high  as  one 
seventh  of  the  entire  number. 

272.  Reasons  for  breathing  through  the  Nose. — (i)  On 
account  of   the  projections  of   the  turbinated  bones  and 
processes  into  each  nasal  passage  and  the  round-about  way 

163 


164  ELEMENTS   OF  PHYSIOLOGY 

the  air  takes  in  passing  through  the  nose  instead  of  the 
mouth,  nasal  breathing  brings  the  air  in  contact  with  a 
much  larger  extent  of  moist  and  warm  mucous  membrane 
than  does  mouth  breathing.  The  air  becomes  warm  and  does 
not,  like  cold  air,  irritate  the  trachea  and  bronchial  tubes. 
(2)  The  air  becomes  purified,  because  the  hairs  just  within 
the  nostrils  and  the  mucous  lining  of  the  latter  serve  to 
catch  particles  of  dust,  and  the  mucus  has  the  power  of 
destroying  germs.  (3)  While  a  mouth  breather  is  eating, 
sufficient  time  is  not  taken  for  chewing  the  food,  but  it  is 
swallowed  too  soon,  so  urgent  is  the  necessity  for  breathing. 
(4)  In  the  habitual  mouth  breather, 
the  nasal  mucous  membrane,  from  lack 
of  stimulus  of  the  cold  air,  dries  and 
shrinks,  causing  discomfort ;  and  since, 
in  its  dry  condition,  the  circulation 
easily  becomes  obstructed,  there  is  a  pre- 
disposition to  congestion  and  catarrhal 
nasal  affections  and  injury  to  hearing. 
FIG.  142. -The  Facial  EX-  (5)  An  unpleasant  expression  of  the 

pression  when  breathing  . 

through  the  Nose  and  f ace  results  from  mouth  breathing  (Fig. 
when  breathing  through   I42)  the  lower  jaw  recedes,  the  upper 

the  Mouth.  J 

teeth  project,  the  nostrils  are  not  devel- 
oped and  in  a  grown  man  may  be  no  larger  than  during 
childhood.  (6)  A  person  has  greater  endurance  in  mus- 
cular exertion  if  he  breathes  strictly  through  the  nose. 
He  can  hold  out  much  longer,  his  lungs  are  kept  more 
expanded,  and  the  heart  is  not  oppressed ;  and,  after 
a  while,  a  "second  wind"  comes  to  him, — for  instance, 
during  running.  (7)  The  voice  has  more  resonance  if  the 
nasal  passages  are  open. 

A  Scotch  physician,  fully  appreciating  the  importance  of 
proper  breathing,  has  written  a  valuable  medical  paper, 
entitled,  "  Shut  your  Mouth  and  Save  your  Life."  Some- 
times the  cause  of  stopping  up  the  nose  in  children  is 


HYGIENE    OF  RESPIRATION  1 6$ 

enlargement  through  glandlike  growth  of  a  structure  in 
the  upper  part  of  the  pharynx  called  the  third  tonsil.  It 
is  just  behind  the  posterior  openings  of  the  nasal  passages, 
and  can  be  easily  removed  if  it  becomes  enlarged.  Per- 
sons who  sleep  with  the  mouth  open  are  likely  to  snore, 
and  the  mouth  and  throat  are  always  dry  in  the  morning. 

273.  Do  the  Breathing   Muscles  rest?  —  Expand  your 
lungs,  and  see  whether  they  will  contract  of  themselves. 
Contract  your  lungs  and  see  whether  they  will  expand  of 
themselves.     See  whether  you  can  make  waist,  chest,  and 
abdomen  expand  at  the  same  time.     You  learned  that  the 
periods  of  rest  taken  by  the  heart  muscles  amount  to  how 
many  hours  daily  ?     The  breathing  muscles  also  rest  a  con- 
siderable portion  of  the  time ;  with  calm  and  happy  people 
they  rest  more  than  with  people  of  anxious,  unquiet  disposi- 
tions.    We  can  breathe  by  means  of  the  expiratory  muscles 
alone  or  by  means  of  the  inspiratory  muscles  alone,  or  by 
using  each  set  alternately.    When  all  the  breathing  muscles 
are  relaxed,  the  lungs  are  at  rest  in  what  may  be  called  the 
neutral  position,  since  there  is  neither  voluntary  contrac- 
tion nor  expansion.    In  this  position  they  are  of  about  aver- 
age size.    If  now  we  use  the  expiratory  muscles  and  contract 
the  lungs,  the  muscles  may  relax  during  inspiration  which 
follows,  for  it  will  be  accomplished  by  the  elasticity  of  the 
abdominal  walls  and  organs,  and  of  the  cartilages  of  the 
thoracic   cage ;    for   these  were  bent  when  the  cage  was 
pulled  from   the  neutral   position.      Try  this   method  of 
breathing  for  a  few  minutes. 

274.  Or,  on  the  other  hand,  when  the  lungs  are  at  rest 
we  may  breathe  by  using  the  inspiratory  muscles  (Fig.  139) 
(diaphragm,  external  intercostals,  etc.),  thus  expanding  the 
lungs  from  the  neutral  position,  and  allowing  the  muscles 
to  rest,  while  the  elasticity  of  the  parts  forces  out  the  air. 
Try  breathing  in  this  way. 

275.  This  expanded  breathing  has  the  advantage  over 


1 66  ELEMENTS   OF  PHYSIOLOGY 

contracted  breathing,  of  removing  pressure  from  the  heart 
and  large  blood  vessels  in  the  chest,  and  allowing  the  heart 
to  work  with  greater  freedom.  It  also  keeps  the  lungs 
more  expauded.  You  learned  in  another  paragraph  that 
it  is  the  usual  method  of  quiet  breathing;  but  strong, 
contracted  breathing  sends  out  fouler  air  from  deep  in  the 
lungs. 

276.  In  both  of  these  ways  of  using  the  breathing  mus- 
cles, there   is  a  pause  in  the  neutral  position  before  the 
next  breath.     But   in  a  time  of  great  exertion,  as   when 
running,  or  during  a  time  of  excitement  and  in  some  forms 
of  illness,  there  is  no  pause  between  breaths,  and  we  use 
what  may  be  called  continuous  breathing.     Both  when  ex- 
piring and  inspiring,  the  ribs  are   pulled  on   beyond  the 
position  at  which  they  rest.     Thus  the  use  of  the  breath- 
ing muscles  is  continuous,  and  it  is  no  wonder  that  they 
may  get  so  tired  that   they  almost  refuse  to  work  for  a 
moment,    and   we  are  "out  of   breath,"  as  we  say.     The 
heart  is  thumping  so  fast  and  strong  that  the  corpuscles 
are  shot  through  the  lungs  with  unnecessary  speed  and  do 
not  get  even  as  much  oxygen  as  they  would  if  going  more 
slowly.     Continuous  breathing  is  a  wasteful  method  ;  haste 
makes   waste    of   strength,    although  it  may  seem  to   be 
necessary  in  an  emergency.     You  can  really  accomplish 
more  by  quiet,  steady  work.    Anxiety  and  worry,  as  well  as 
great  physical  exertion,  cause  this  hurried,  wasteful  breath- 
ing ;  hence  we  should  cultivate  the  easy  way  of  breathing. 

277.  Reasons  for  Strong  Expiration  and  Inspiration.— 
Purifying  the  air  in  the  lungs  may  be  illustrated  by  dipping 
dirty  water  out  of  a  barrel  and  replacing  it  with  clear  water. 
If  a  dipperful  of  clean  water  is  poured  into  the  barrel  and 
the  same  amount  of  water  is  dipped  out,  this  will  cause  the 
cleanest  water  to  be  at  the  top,  whence  it  will  always  be 
dipped  out  and  the  dirtiest  water  will  be  left.     It  is  the  same 
way  with  the  lungs ;  the  purest  air  in  the  lungs  is  always 


HYGIENE   OF  RESPIRATION 


I67 


removed  by  breathing,  but  if  the  lungs  are  contracted  by 
strong  and  long  expirations,  more  air  from  deep  down  in 
the  lungs,  and  therefore  fouler  air,  is  removed.  When  the 
lungs  expand  fully,  their  surface  is  increased  and  every 
little  air  cell  is  opened,  helping  the  exchange  of  carbon 
dioxid  and  oxygen  through  the  thin  walls. 

278.    You  have   just    been    studying    about   the    three 
methods  of  breathing  according  as  you  use  (i)  the  inspira- 


FiG.  143. 


FIG.  144. 


FIG.  145. 

Diagrams  illustrating  Proper  and  Improper  Methods  of  Breathing. 

Dotted  lines  show  area  of  expansion. 

Fig.  143.  —  Female  figure  encased  in  corset.  Expansion  at  the  waist  is  here  impossible 
and  the  breathing  is  called  "  collar  bone  breathing." 

Fig.  144.  —  Male  figure.  Here,  owing  to  pressure  of  clothing  and  faulty  position,  expan- 
sion of  chest  is  impeded  and  breath  is  taken  by  the  "  diaphragmatic  method." 

Fig.  145.  —  Figure  properly  poised  and  free  from  constriction.  Here  the  entire  thorax 
can  move  freely  and  normal  breathing  is  the  result. 

tory  muscles,  (2)  the  expiratory  muscles,  (3)  both.  The 
breathing  may  be  varied  also  by  the  activity  of  the  muscles 
prominent  in  (i)  the  abdomen,  (2)  the  chest,  (3)  both. 
This  gives  rise  to  — 

279.  Abdominal  Breathing,  Chest  Breathing,  and  Full 
Breathing.  —  See  whether  you  can  make  waist,  chest,  and 
abdomen  expand  at  the  same  time.  See  whether  you  can 
make  waist,  chest,  and  abdomen  contract  at  the  same  time. 


1  68  ELEMENTS  OF  PHYSIOLOGY 

There  has  been  much  discussion  among  physicians,  voice 
trainers,  and  elocutionists  as  to  the  proper  way  to  breathe, 
some  advocating  chest  breathing  (Fig.  143),  and  some  ad- 
vocating abdominal  or  diaphragmatic  breathing  (Fig.  144). 
The  fact  that  so  elementary  a  process  as  breathing  is  still 
a  subject  of  discussion  illustrates  how  imperfect  is  the 
state  of  our  physiological  knowledge,  especially  when 
an  attempt  is  made  to  apply  it  to  practical  purposes.  The 
author  believes  that  pure  chest  breathing  and  diaphrag- 
matic breathing  are  both  wrong,  and  that  what  may  be 
termed  full  breathing  is  the  natural  and  best  way  (Fig.  145). 

280.  Full  breathing  employs  movement  of  both  chest 
and  diaphragm,    the  greatest  expansion  being  in  neither 

Chest  n°r  abdomen>  but  at 
the  waist,  and  diminishing  in 

amount  both  upward  and  down- 
ward.  The  objection  to  pure 
chest  breathing'^  that  the  marked 

m°vement  °f  the  upper  part  °f 

the  bony  caSe  recluires  exhaust- 
4.  MAN  IN  CORSET  mg  effort  ;  such  movement  can 

be  employed  without  waste  of 
strength  for  only  a  short  period, 
as  in   gasping    for    breath  _or 
REFORMED  CORSET  WEARER  during  great  muscular  exertion 

FIG.  l46.-BreaThing  Tracings       (5  263>       Yet  Some  women  with 

(Kellogg).  waists  confined  by  tight  clothing 

Motion  of  chest  recorded  at  left  and  of  breathe  in  this  way  f  or  hours  at  a 

waist  at    right.  tjme  .    thus    their    strength  WCarS 

out,  and  they  are  old  before  their  time  (Fig.  146). 

281.  In  full  breathing,  the  diaphragm  contracts  but  at  the 
same  time  the  ribs  are  lifted  upward  and  outward,  and  the 
points  of  attachment  of  the  diaphragm  are  thus  raised  and 
separated  so  that  the  diaphragm  flattens  without  any  great 
descent.     But  in  pure  abdominal  breathing,  the  movement 


wou,  CORBET 


HYGIENE   OF  RESPIRATION  169 

is  confined  to  the  diaphragm  and  abdomen,  and  lateral 
action  of  the  chest  is  suppressed.  The  effect  of  this  is  to 
cause  too  great  a  displacement  downward  of  the  liver, 
stomach,  kidneys,  colon,  and  other  organs.  But  in  nor- 
mal or  full  breathing,  any  great  degree  of  downward 
movement  is  prevented  by  expansion  of  the  trunk  at  the 
waist.  In  abdominal  breathing,  the  abdominal  walls  are 
entirely  relaxed  as  the  diaphragm  descends,  and  the 
liver  and  other  organs  are  moved  but  not  compressed. 
In  full  breathing  they  are  compressed  and  slightly  moved, 
and  the  compression  squeezes  the  blood  out  of  them 
toward  the  heart  and  presses  the  lymph  upward  through 
the  thoracic  duct;  the  expansion  of  the  chest  at  the 
same  time  helps  to  draw  the  blood  upward.  During 
expiration  fresh  blood  is  sent  back  to  the  abdominal 
organs,  and  so  they  are  kept  fresh  and  strong.  Ladies 
who  wear  skirts  with  bands  tight  enough  to  support  them 
at  the  waist,  and  men  who  support  their  trousers  by  buc- 
kling them  around  the  waist,  gradually  lose  the  power  of 
lifting  the  ribs  outward  at  the  waist.  This  expansion  is 
most  important  for  good  breathing,  because  the  lungs  are 
largest  there. 

282.  Effect  of  Alcohol  upon  the  Lungs.  —  It  was  learned 
that  alcohol  paralyzes  the  vasomotor  nerves,  or  those 
that  control  the  size  of  the  blood  vessels.  This  allows  the 
smaller  arteries  in  the  lungs  to  swell  and  the  capillaries  to 
become  congested,  crowding  upon  the  air  cells  and  diminish- 
ing the  breathing  power  of  the  lungs,  as  is  readily  shown  by 
the  use  of  the  spirometer,  a  simple  instrument  which,  when 
the  breath  is  blown  into  it,  measures  the  number  of  cubic 
inches  the  lungs  expand.  The  continual  congestion  of  the 
lung  tissue  results  in  an  abnormal  growth  of  connective 
tissue  fibers  in  the  walls  of  the  cells ;  the  walls  thus  be- 
come thickened  and  hardened  and  obstruct  the  absorption 
of  the  oxygen  and  the  escape  of  the  carbon  dioxid.  Besides 


I/O  ELEMENTS   OF  PHYSIOLOGY 

this,  alcohol  injures  the  red  corpuscles,  causing  them  to 
shrink  and  impairing  their  power  to  receive  and  carry  oxygen. 
All  these  changes  diminish  the  oxygen  in  the  blood.  This 
state  of  blood  is  plainly  shown  in  the  purplish  face  of  the 
drunkard,  crowded  with  enlarged  veins.  The  weakened 
power  of  breathing  explains  why  a  man  given  to  drunken- 
ness cannot  endure  vigorous  muscular  exertion  so  long  as 
can  a  healthy  person. 

283.  The  injurious  effects  described  readily  explain 
why  the  consumption  that  attacks  inebriates  is  a  very 
rapid  and  fatal  form  of  the  disease. 

•284.  Effect  of  Tobacco  upon  the  Respiratory  Organs. — 
The  hot  smoke  irritates  and  dries  the  mucous  membrane 
of  the  mouth  and  throat,  producing  an  unnatural  thirst 
that  may  readily  lead  to  the  use  of  alcoholic  drinks.  In- 
haling the  poisonous  smoke,  which  occurs  to  the  greatest 
degree  in  cigarette  smoking,  inflames  the  delicate  mucous 
lining  of  the  bronchial  tubes  and  air  cells.  There  may 
result  from  this  an  irritating  cough,  short  breath,  and 
chronic  bronchial  catarrh. 

285.  Ventilation.  —  The  evil  effects  of  re-breathing  air 
can   hardly   be   exaggerated.     The    blood   stagnates,   the 
heart  acts  slowly,  the  brain  is  clogged,  the  head  aches,  and 
either   a   dull  or  a   feverish    feeling    arises.     The   body 
becomes  sensitive  to  cold.     The  skin  becomes  pale,  the 
blood  is  loaded  with  impurities,  and  the  whole  body  is  ob- 
structed with  refuse  material.     In  such   a   human  body, 
colds,    catarrh,    consumption,  and    other   diseases  readily 
develop.     The    constant   breathing   of   even   the  slightly 
impure  air   of    most  private  houses   cannot   but   tend  to 
undermine  the  health  and  prevent  that  perfect  soundness 
of  body  which   thorough   ventilation  or  life   in  the  open 
air  insures. 

286.  Judgment  with  regard  to  ventilation  is  rare.     In 
many  churches  and  assembly  rooms  the  windows  are  tightly 


HYGIENE  OF  RESPIRATION  171 

closed  except  in  warm  weather.  If,  during  the  meeting, 
the  room  becomes  too  warm  (not  if  it  becomes  foul  with 
impure  air),  some  one  will  open  one  or  more  windows  to 
their  full  height ;  the  strong  draught  soon  cools  the  room 
and  chills  some  one,  whereupon  he  goes  to  the  window 
and  shuts  it  tight.  One  absurd  extreme  thus  follows 
another.  All  that  was  necessary,  if  there  was  no  scien- 
tific provision  for  ventilation,  was  for  all  of  the  windows 
to  have  been  opened,  for  an  inch  or  less,  when  the  as- 
sembly began,  and  allowed  to  remain  so ;  then  no  one 
would  have  been  too  hot  or  too  cold,  or  would  have 
suffered  from  foul  air. 

287.  What  is  the  probable  cause   of   persons   fainting 
or   going   to    sleep    in    church  ?     With    the   foul   air  was 
combined  what  other  disadvantage  to  breathing,  as  shown 
by  one  of  the  measures  often  taken  to  restore  a  person  in 
a  faint,  especially  if  a  woman  ? 

288.  The  ventilation  of  the  schoolroom  is  often  deplor- 
able.    A  visitor,  upon   entering  a  schoolroom,  especially 
if  the  school  has  been  in  session  for  an   hour  or   more, 
may  notice  a  stifling,  foul-smelling  atmosphere.     The  chil- 
dren have  rushed  in  from  their  active  games  with  their 
clothing  saturated  with  perspiration.     Their  healthy  skins 
perspire  more  freely  than  do  those  of  adults.     Some  of 
them  may  have  coughs    or    colds,    and   sometimes   come 
from  sick  rooms. 

289.  Carbon  monoxid  forms  in  the  stove  if  the  draught 
is  closed  too  much,  and  escapes  through  cracks  and  seams 
in  the  stove,  and,  if  the  stove  is  red-hot,  through  the  iron 
itself.      Carbon   monoxid  is  different   from  the  dioxid  in 
being  imperfectly  oxidized,  and  its  attraction  for  oxygen 
causes  it,  when  breathed,  to  attack  the  red  corpuscles  of 
the  blood    causing  headache  and  dizziness,  for  the  mon- 
oxid  is   an   active  poison,  not  merely  negative    like   the 
dioxid.      The   ashes  from  the  stove,  the    dust  from   the 


1/2  ELEMENTS   OF  PHYSIOLOGY 

pattering  of  many  feet,  the  clouds  of  chalk  dust,  accumu- 
late until  they  become  almost  unbearable,  and  all  that  gets 
out  leaves  the  room  on  the  clothes  of  the  pupils,  or  on  the 
mucous  membrane  of  their  nasal  passages,  windpipes,  and 
lungs;  for  the  janitor  is  more  ignorant  than  the  house- 
keeper, and  he  likewise  will  not  open  the  windows  before 
sweeping  because  of  the  trouble ;  or,  if  persuaded  to  open 
them,  he  must  be  compelled  by  the  principal  to  allow  them 
to  remain  open  for  the  dust  to  blow  out,  otherwise  he 
will  close  them  on  leaving  each  room  to  avoid  the  annoy- 
ance of  returning. 

290.  These  are  the  conditions  of  many,  many  school- 
rooms and  houses,  for,  unfortunately,  some  persons'  knowl- 
edge of  physiology  consists  largely  of  a  knowledge  of  big 
names.     It  is  not  strange  that  lung  troubles  are  rife,  and 
that   people  wonder  whence  they  come,  and   take  medi- 
cated  gases   instead  of   pure  air.     Many  of  the  Indians 
of  Patagonia   died   of   consumption   within   nine   months 
after  being  taught  by  the  missionaries  to  live  in  houses. 

291.  It  is  necessary  to  give  children  knowledge  of  the 
geography  of  Africa  and  other  remote  lands,  but  it  is  at 
least   as   necessary    to   train    them    to   sit   and   to   stand 
correctly.     Interruptions  to  study  every  half  hour  by  calis- 
thenic  exercises   so   selected    as   to   give   vigor  to   those 
muscles  that  counteract  the  evil,  deforming  effects  of  pro- 
longed sitting,  would  help  them  to  grow  up  well-formed 
men  and  women,  and  would  aid  in  learning  the  geography 
as  well. 

292.  The  health  of  children  at  school  often  suffers,  and 
parents  usually  think  it  is  because  of  the  number  of  studies. 
This  idea  is  no  doubt  largely  erroneous.     The  breathing  of 
the  bad  air,  both  at  home  and  at  school,  the  close  confine- 
ment in   the    schoolroom,  sitting  in  a   cramped   position, 
and  studying  by  improper   light,  are  the  true  causes   in 
a  majority  of  cases. 


HYGIENE    OF  RESPIRATION 


173 


293.  Some  persons  in  their  anxiety  for  pure  air  become 
extremists,  and  forget  that  the  body  may  likewise  be  in- 
jured by  cold.     In  ventilating  a  room,  not  one  but  two 
purposes  must  be  kept  in  view :  to  furnish  air  that  is  pure, 
and  air  at  the  proper  temperature. 

294.  Methods  of  Ventilation  depend  upon  the  principle 
that  hot  air  is  lighter  than  cold  air  and  is  pushed  up  by 
it.     If  you  have  two  openings  for  ventilation,  one  higher 
than   the   other,    at   which   opening   does   the   warm   air 
go  out  ?     If  the 

higher  opening 
is  near  the  ceil- 
ing, do  the  per- 
sons in  the  room 
get  the  coldest  or 
the  warmest  air? 
Does  such  a 
method  econo- 
mize the  fuel? 
If  the  inlet  is 
near  the  floor, 
why  should  the 
stove  be  near 


FIG.  147.  —  The  Proper  Method  of  ventilating  a  Room. 

The  stove  is  on  the  side  toward  the  cold  winds.  The  inlet  is 
near  the  stove,  the  outlet  farthest  away.  If  the  window  near 
the  stove  were  lowered  from  the  top,  what  would  probably 
happen?  If  another  window  near  the  stove  were  opened, 
what  might  happen?  If  the  prevailing  cold  winds  came  from 
the  opposite  direction,  what  changes  should  be  made  in  the 
room?  How  do  you  ascertain  whether  the  outlet  fails  to  serve 
its  purpose  and  becomes  an  inlet? 

the  inlet  ?     Why  should  the  outlet  be  on  the  side  of  the 
room  farthest  from  the  stove  ? 

295.  Good  ventilation  is  arranged  so  that  the  fresh  air 
shall  be  heated  before  or  just  after  it  enters  the  room,  and 
that  it  shall  pass  across  the  room  in  order  that  the  in- 
mates may  get  the  benefit  of  both  its  warmth  and  its  purity 
before  it  passes  out  (Fig.  147).  Test  the  direction  of  the 
air  currents  in  your  bedroom  and  in  your  schoolroom  by 
means  of  a  spider  web  hanging  from  the  end  of  a  stick. 
Why  is  it  best  not  to  have  the  outlet  on  the  side  of  the  house 
toward  the  prevailing  wind  in  winter  ?  If  the  inlet  is  so 
situated  that  the  cold  air  does  not  pass  over  the  stove,  a 


174 


ELEMENTS   OF  PHYSIOLOGY 


FIG.  148. 


board  or   a  screen  may  be  placed  before  the  window  to 

deflect  the  current  upward  and  prevent  its  chilling  those 

seated  nearest  the  window  (Fig.  148).  If  you  find  by 
holding  your  hand  near  the  inlet  that  there  is 
a  good  inward  current,  you  may  be  sure  there 
is  sufficient  outlet;  although  if  it  is  not  far 
enough  from  the  stove,  heat  will  be  wasted. 
If  you  know  there  is  a  strong  outward  cur- 
rent, for  instance,  when  a  fire  is  burning  in  an 
open  fireplace,  you  may  be  sure  that  the 
same  amount  of  air  is  '  entering  somewhere, 
if  only  through  minute  cracks  (Fig.  150). 

296.  When  over-enthusiastic  people  become 
interested  in  ventilation,  they  sometimes  in- 
jure themselves  by  chilling  draughts  and  low 
temperatures.  The  temperature  of  the  room 
^ou\d  be  kept  between  65  and  70  degrees. 
wooden  strip  at  a.  The  foregoing  directions  for  ventilation  apply 

to  cold  weather.     For  warm  weather  no  special  directions 

are  necessary,  for  most  people  are  more  unwilling  to  bear 

unpleasant  heat  or  to  soil  their 

collars  with  perspiration,  than 

to  breathe  foul  air. 

297.   The  Five  Degrees  in 

Cleanliness.  —  Nearly  all  peo- 

ple are  very  careful  to  wear 

clothes  that  are  perfectly  neat 

and  clean.     Dust  or  mud  upon 

their  clothes  is  considered  the        FIG.  149.  —  Gallon's  Fire  Grate. 

highest  degree  of   uncleanli-   With  a  Pasusase  bejind.  the  grate  that  the 

air  may  be  heated  as  it  enters. 

ness.     Many  think  it  of  the 

highest  importance  to  health  and  refinement  to  keep  the 
skin  clean  by  regular  baths.  But  there  are  a  few  that 
think  it  of  still  greater  importance  to  keep  the  air  clean 
that  goes  into  the  lungs.  A  few  also  think  it  necessary  to 


a-* 


HYGIENE   OF  RESPIRATION 


175 


keep  the  alimentary  canal  pure  throughout  by  reasonable 

eating  and  living.     We  also  meet  with  those  who  believe 

not  only  that  the  clothes,  the  skin,  the  lungs,  the  digestive 

organs,  must  be  kept  clean,  but 

that  the  blood  must  be  clean  and 

fresh,  ever  renewed  by  a  strong 

and  vigorous  flow,  and  they  so 

live  that   as   far  as  possible  it 

shall  always  be  so.     The  daintily 

dressed  lady  or  the  dandified  man 

would  be  horrified  at  a  particle 


Of  mud  that  fell  Upon  the  Clothes,    Fia  I50._  Ventilation  by  an  Ordi- 
but   Sometimes  if    yOU  are  SO  Un-  nary  Grate  or  Fireplace. 

fortunate  as  to  catch  a  whiff  of         The  coldest  air  chills  the  feet- 

the  breath  of  such  a  person,  its  repulsive,  sickening  odor 
shows  that  foulness  and  uncleanliness 
have  taken  possession  of  the  lungs,  or 
digestion,  or  blood.  We  should  be 
careful  to  observe  these  five  degrees 
of  cleanliness,  but  which  should  we 
value  most  highly  ?  There  is  still 
another  degree  in  cleanliness,  or  pur- 
ity, which  concerns  purity  of  mind 
and  nobility  of  soul. 

298.  The  Mistake  of  the  Overstu- 
dious. — The  pale  student,  thinking 
only  of  the  desire  for  learning  aroused 
by  teacher  or  parents,  and  neglecting 
the  promptings  of  his  natural  instincts 
toward  complete  living,  thinks  he  is 
doing  wisely  and  right  when  he  is 
constantly  delving  into  books.  On 
the  contrary,  he  is  sinning  against 

part  of  his  nature  and  unfitting  himself  for  accomplishing 

the  best  work  he  is  capable  of  doing. 


FIG.  151. 

The  air  enters  through  a  special 
inlet  and  is  warmed  as  it 
passes  through  a  hood  sur- 
rounding the  stove. 


176  ELEMENTS   OF  PHYSIOLOGY 

299.  Consumption,  or  Tuberculosis,  is  a  disease  due  chiefly 
to   living  constantly  in  unventilated    houses.      That  the 
natural  curative  powers  of  the  body  are  capable  of  curing 
consumption,  is  shown  by  the  fact  that  reports  of  post- 
mortem  examinations   in   some   of   the   hospitals   of   the 
United  States  and  Europe  show  scars  on  the  lungs  in  half 
of   the   cases  examined.     These  scars  were   left  by  con- 
sumption, which  the  persons  had  had  without  knowing  it  or 
being  treated  for  it,  and  from  which  they  had  entirely  re- 
covered, dying   afterward   from  another  disease.     These 
facts  show  that  in  the  early  stage  consumption  is  an  es- 
pecially curable  disease.     Persons  are  sometimes  alarmed 
because  they  have  heard  that  consumption  is  caused  by  a 
bacillus,  or  microscopic  germ,  commonly  called  a  microbe. 

300.  That  it  is  not  caused  by  microbes  alone  is  proved 
by  the  fact  that  the  microbes  are  floating  in  the  air,  and 
nearly  all  human  beings  are  exposed  to  them  many  times 
in  their  lives,  yet  all  do  not  contract  the  disease.    Consump- 
tives are  constantly  spitting  on  the  streets  of  cities,  yet  a 
smaller  percentage  of  the  street  cleaners  of  Berlin  than 
of  almost  any  other  class  of  the  population   die  of   con- 
sumption. 

301.  Outdoor  life,  simple  diet,  and  exercise  seem  to  be 
the   best  treatment.      Inhalations   through   apparatus  of 
medicated  air,  moist  air,  dry  air,  cold  air,  superheated  air, 
air  charged  with  the  pleasant  aroma  of  pine  leaves  or  the 
repulsive  sulphuret  of  hydrogen,  have  all  been  tried.    It 
seems  impossible  directly  to  destroy  the  microbes   when 
they  once   obtain  a  foothold  in   the  lungs,  without   the 
employment  of  such  measures  as  will  destroy  the  lung 
tissue  as  well  as  the  parasitic  bacilli.     Even  if  the  bacillus 
could  be  destroyed  by  germicides,  it  would  be  impossible, 
since  the  germs  are  so  widely  scattered,  to  escape  infection 
again,  and  the  disease  would  return  for  the  same  reason  that 
it  first  gained  a  foothold :  this  was  because,  from  indoor 


HYGIENE   OF  RESPIRATION  1 77 

life,  shallow  breathing,  indigestion,  lack  of  exercise  and 
fresh  air,  the  blood  had  become  impure  and  the  lung 
tissue  so  corrupted  and  weakened  that  it  furnished  a  fer- 
tile soil  for  the  growth  of  the  germs.  (Read  note  2,  page 
191.) 

302.  Subject  for  Debate. — Resolved,  That  the  Chinese 
woman  has  less  love  for  personal  deformity  than  the  Cau- 
casian woman  and  suffers  less  from  it. 

BACTERIA   AND   DISEASE 

303.  Nature  of  Germ  Diseases.  —  A  plant,  as  an  oak  or  a 
pear  tree,  may  become  affected  by  a  disease  called  the 
blight,  and  such  disease  is  usually  regarded  as  a  necessary 
evil,  or  an  imperfection  in  creation.     Looked  at   with   a 
broader  knowledge,  such  disease  is  a  sign  of  growth  as  well 
as  of  decay  and  is  a  blessing  and  not  a  curse.     The  micro- 
scope shows  that  trees  affected  with  the  blight  are  the  seat 
of  the  growth  of  millions  of  one-celled  plants  called  bacteria. 
So  where  there  is  death  and  disease,  there  is  flourishing 
life.     The  blight  did  not  attack  the  hardy,   sound  pear 
trees,  but  those  of  rapid,  sappy  growth  whose  tissues  had 
already  become  injured  or  dead  by  the  effect  of  frost  or 
some  other  agent.     The  function  of  the  bacteria  is  to  de- 
stroy unsound  vegetable  or  animal  matter  by  living  upon  it 
as  food,  thus  decomposing  it  and  returning  it  to  the  soil 
and  the  air  to  be  used  again.     There  is  no  decay  without 
the  action  of  bacteria;    without  it  organic  matter  would 
accumulate    indefinitely,    interfering   with   life   upon   the 
earth. 

304.  Molds.  —  Every  one  has  seen  fungus  plants,  such  as 
mushrooms  and  puff-balls,  that  do  not  bear  flowers  but  mul- 
tiply by  spores.     They  live  upon  dead  logs  or  where  there 
is  much  dead  organic  matter  in  the  soil.     Imagine  a  fun- 
gus that  grows  on  an  average  about  yj-g-  of   an  inch  in 


178  ELEMENTS   OF  PHYSIOLOGY 

height;  this  is  called  mold  (Fig.  152).  It  grows,  for 
instance,  upon  moist  bread  in  warm  weather.  Mold  forms 
a  kind  of  network  as  it  grows  through  any  substance  that 
N  will  nourish  it,  and  sends  up  stalks  with 
knoblike  ends,  the  knobs  being  full  of 
minute  spores. 

305.  Yeast  —  Think,  if  you  can,  of 
small  plants  only  about  ^  for  of  an  incn 
in  length,  composed  usually  of  one  oval 
cell,  a  plant  that  makes  new  plants  by 
"budding,"  or  the  forming  of  a  smaller 
FIG.  152.  —  Ring-  cel1  on  tne  olc*  one.  Yeast  cakes  consist 
worm  Fungus  in  a  of  yeast  plants  scattered  among  the  grains 

wiif  Fig.(^mpare  of  flour  of  which  the  cake  was  made- 

Yeast  plants  multiply  rapidly,  doubling  in 
number  in  two  hours  (Fig.  153).  They  grow  upon  sugar, 
decomposing  it  into  alcohol  and  carbon  dioxid.  This  pro- 
cess is  called  fermentation.  In  wine  making,  alcohol  is  the 
product  sought;  in  bread  making,  carbon  dioxid 
is  the  useful  product,  this  gas  giving  the  bread 
its  lightness,  while  the  small  amount  of  alco- 
hol formed  is  driven  out  by  the  heat  in 
cooking. 

306.   Bacteria.  —  But    suppose   the    micro- 
scope shows  a  much  smaller  vegetable  organ-  FIG.  153.  —  The 

..   ,  r  •      L     •  Yeast  Plant- 

ism  which    averages    ^oWoo"   °f   an   mc^  m 


diameter  and  is  a  one-celled  vegetable  that  multiplies  by 
division  like  the  ameba  and  other  one-celled  animals,  and 
lives  upon  albuminous  substances  only  for  its  food.  This 
is  a  bacterium.  Bacteria  are  called  also  microbes  or 
germs  ;  and  they  are  the  smallest  of  living  organisms.  A 
bacterium  that  is  rod-shaped  is  called  a  bacillus  (Fig. 
154).  Under  favorable  conditions  —  abundance  of  food 
and  considerable  warmth  and  moisture  —  bacteria  may 
double  in  numbers  every  half  hour.  Thus  millions  may 


HYGIENE    OF  RESPIRATION  179 

result  from  even  one  in  a  short  time.  (You  will  compre- 
hend this  better  by  referring  to  "geometrical  progression  " 
in  your  arithmetic.)  Dryness  and  cleanliness  prevent  their 
growth ;  cold  retards  their  growth  and  division,  hence  the 
utility  of  ice  in  preserving  meat,  milk,  fruits,  and  other 
foods  in  warm  weather. 

307.  Can  you  now  arrange  the  names  yeast,  mold,  and 
bacterium  in  order  of  size  ?      Can  you 

give  the  kind  of  material  that  each 
uses  for  food  ?  Can  you  tell  how  each 
multiplies,  or  reproduces  its  kind? 
What  is  a  bacillus  ?  For  what  is  "  mi- 
crobe  "  another  name  ? 

308.  Use  of  the  Small  Organisms. — 
Molds  are  nature's  tools  for  destroying 

hard  and  durable  tissue  like, logs,  bone,  FIG.  154.  —  Bacilli;  the 
and  hides,  which  otherwise  would  not  fame  S,peci?  masni' 

fiedtoTwo  Sizes. 

decay  but  would  fill  the  earth,  leaving 
no  room  for  living  creatures.  Ringworm  is  caused  by 
the  growth  of  one  form  of  mold  within  the  skin.  It  does 
not  grow  in  a  sound  and  clean  skin.  Falling  of  the 
hair  is  often  accompanied  by  the  growth  of  mold  in  the 
hair  follicles,  but  it  must  be  preceded  by  overheating  and 
starving  of  the  cells  of  the  scalp  by  a  tight  hat,  too  much 
brain  work,  or  other  cause  (Fig.  152).  Yeast  prevents 
the  calamity  of  all  plant  food  accumulating  in  the  form 
of  starch  and  sugar.  Bacteria  destroy  the  dead  and  excreted 
matter  of  vegetables  arid  animals  so  that  it  melts  away  and 
is  stored  in  the  soil,  ready  to  be  utilized  as  plant  food 
again.  Mold,  yeast,  and  bacteria  are  great  blessings,  for 
they  are  indispensable  friends  of  all  other  living  beings 
(Fig.  I55> 

309.  Their  Work  in  the  Body.  —They  do  not  always  wait 
for  the  dead  or  dying  material  to  be  excreted,  or  separated 
from  the  animal  or  plant,  before  attacking  and  destroying 


ISO  ELEMENTS  OF  PHYSIOLOGY 

it.     If  more  food   is  eaten  than  can  be  digested,  and   it 
remains  longer  than  five  hours  in  the  stomach,  starchy  food 
may  ferment  from  yeast  plants,  giving  rise  to  carbon  dioxid 
gas,  and  albuminous  food  may  ferment  from  bacteria,  or  a 
moldy  growth  may  form  on  the  lining  of  the  organs,  extend- 
ing up  to  the  mouth 
and   forming   a   coat 
upon  the  tongue.     If 
the  lungs   are   never 
fully    expanded,    but 
by  stooping   over   at 
work     or     by     tight 
clothing  a  part  of  the 
lungs   is   compressed 

j  yy§jS^j5|  ^  and  the  blood  supply 

QOQ  "  25°C  interfered  with,  or  if 

FIG.  I55.-Shown  by  Microscope  of  High  Power.   f°ul   air   is  Constantly 

A,  white  corpuscles  are  seen  creeping  up  a  tube  and  devour-  breathed,       impurities 
ing  bacteria  which  appear  as  minute  specks.  maV       Collect       in      the 

B,  a  drop  of  water  containing  infusoria.    The  clump  in  the  * 

middle  has  been  killed  by  the  touch  of  a  hot  needle,  the  lungS     and      the  baC- 

others  are  fleeing  from  the  dead  bodies.                                           .                             . ,  •• 

C,  a  capillary  glass  tube  containing  bacteria.     One  end  is  tCHa  are  On    the  alert 
heated  to  25° C,  the  other  end  cooled  too0  C.     The  bac-  to  remove  them  The 
teria  have  crowded  to  the  warm  end. 

bacillus    tuberculosis 

is  the  form  of  bacteria  that  usually  finds  lodgment  in  the 
lungs. 

310.  As  the  bacilli  multiply  tiny  tubercles  are  formed ; 
hence  the  name.  Tubercles  are  growths  shaped  like  pin 
heads,  and  they  may  be  formed  in  any  tissue  of  the  body. 
An  attack  of  consumption  is  usually  preceded  by  indi- 
gestion and  imperfect  nutrition  of  the  body.  You  have 
learned  that  in  thousands  of  cases  bacilli  remove  an  injured 
part  of  a  lung  and  it  heals  over.  But  in  thousands  of  cases 
the  individuals  have  lived  wrong  physically  for  so  long, 
and  their  lungs  have  become  so  weak,  that  they  are 
gradually  destroyed  by  the  bacilli.  This  is  sad  to  the 


HYGIENE    OF  RESPIRATION  il 

individual  and  his  friends  and  loved  ones,  but  it  is  best 
for  the  race,  for  it  prevents  gradual  degeneration  into  a 
race  of  weaklings. 

311.  Whether  the  body  has  been  injured  through  ig- 
norance or  self-sacrifice,  through  dissipation  or  selfish  am- 
bition for  money   or   fame,   through  foolish  attempts  at 
beauty  or  through  devotion  to  learning,  or  through  unselfish 
love  and  work  for  others,  the  result  is  the  same ;  nature 
knows  no  difference.     However  noble  the  character  or  wise 
the  mind  (in  other  directions),  when  a  vital  organ  has  sunk 
in  health  below  the  standard  necessary  for  a  human  being, 
condemnation  comes. 

312.  Bacilli  are  usually  found  in  the  sputum  only  in  an 
advanced  stage  of  consumption.     Then  recovery  is  more 
difficult,  but  it  will  often  come  if   the  person  returns  to 
natural  ways,  living  out  of  doors  and  allowing  the  forces 
of  health  to  purify  the  body. 

313.  Effects  of  Bacteria.  —  You  learned  that  they  produce 
decay  in  unsound  tissue.     They   destroy   the  albumin  in 
which  they  grow,    producing    foul-smelling  gases   and  a 
number  of  poisons  called  ptomaines,  if  formed  after  death. 
Ptomaines  cause  most  of  the  symptoms  produced  by  eating 
decayed  meat.      A  special  kind   of   ptomaine  sometimes 
forms  in  milk  and  ice  cream  which  has  been  kept  for  a  long 
while.     This  is  why  ice  cream  which  has  been  melted,  and 
frozen  a  second  time,  is  dangerous. 

314.  The    growth   of    bacteria    in    an    unsound,   living 
body,  produces    poisons  called   toxins,  which,   circulating 
among  the  sound  tissues,   produce  weakness  and  disease. 
Disease  germs  may  grow   upon    the    injured  cells  in  an 
open  wound,  causing  offensive  matter  to  form.      In  severe 
cases  they 'cause  swelling  of  the  surrounding  parts,  with 
erysipelas  or  blood  poisoning.     Diphtheria,  typhoid  fever, 
consumption,     cholera,    lockjaw    and    la    grippe    are    all 
diseases  in  which  germs  have  been  proved  to  be  present. 


1 82  ELEMENTS   OF  PHYSIOLOGY 

Typhoid  fever,  for  instance,  is  usually  contracted  through 
the  use  of  water  from  an  impure  source.  There  have 
been  cases  of  a  spring  or  well  becoming  infected  with  the 
typhoid  germs  and  giving  typhoid  fever  to  the  unhealthy 
members  of  every  family  that  used  water  from  it.  It 
reqtdres  many  bacteria  to  produce  infection  ;  to  cause  some 
diseases  several  millions  are  necessary.  Certain  kinds  of 
communicable  diseases  can  be  caught  only  by  coming  in 
contact  with  the  sick  person,  or  with  some  article  that  he 
has  touched,  or  by  going  into  the  room  where  he  is  sick. 
These  diseases  are  said  to  be  contagious,  since  they  are 
caught  by  actual  contact.  Diseases  that  are  transmitted 
through  the  air,  contact  being  unnecessary,  are  said  to  be 
infectious.  Measles,  scarlet  fever,  mumps,  whooping  cough, 
and  smallpox  are  contagious  diseases,  and  germs  are  sup- 
posed to  be  necessary  for  their  existence,  but  no  germ  has 
ever  been  found. 

315.  It  has  never  been  proved  that  germs  will  cause 
harm  or  disease  to  a  perfectly  healthy  body.     The  germs 
that  produce  boils  enter  the  skin  at  some  scratch  or  break 
that  reaches  the  lymph  spaces.     But  a  person  with  pure 
blood  and  lymph   could  have  a  number  of  breaks  in  the 
skin  and  would  probably  not  have  a  single  boil.     Some 
germs  seem  to  change  their  nature  or  the  nature  of  the 
toxins  they  form,  according  to  the  material  upon  which 
they  live.     Many  germs  seem  to  be  harmless  when  living 
in  certain  conditions,  but,  if  they  find  a  diseased  condition, 
they  seem  to  change  their  nature  and  begin  the  forma- 
tion of  poisonous  toxins.     This  is  known  to  be  true  of  the 
colon  bacillus  and  other  germs. 

316.  How  Bacteria  are  destroyed  within  the  Body.  —  The 
body  of  one  who  is  worthy  of  physical  health  has  three 
very  efficient  means  of  defense  : 

First.  —  The   white  blood  cells  have  it  for  their  chief 
function  to  seek  out  bacteria  and  to  devour  and  destroy  them 


HYGIENE    OF  RESPIRATION  183 

(Fig.    156).     This  explains  why  so  many  germs  are  neces- 
sary to  transmit  a  disease. 

Second.  —The  plasma  of  the  blood  and  lymph,  and  even 
mucus,  are  able  in  some  unknown  way  to  destroy  germs  of 
disease. 

Third.  —  The  serum  of  the  blood  often  develops  a  sub- 
stance called  an  antitoxin, 
which  poisons  the  germs 
and  stops  their  action. 
When  the  disease  has  pro- 
gressed for  a  time,  the  anti- 
toxin is  formed  in  sufficient 
quantities  to  kill  the  germs 
and  the  disease  is  cured. 

a,  germ  destroyed  by  white  blood  cell;  o,  cell 
317.     Malarial  fever  arises         destroyed  by  germs  and  the  germs  multiply- 

f rom  the  presence  of  a  one-  ing' using  the  ceU  for  food 
celled  animal  similar  to  the  ameba,  that  lives  through  one 
phase  of  its  existence  in  the  body  of  a  certain  kind  of 
mosquito  (Fig.  157),  and  reaches  the  human  system  by  the 
mosquito's  bite.  It  then  multiplies  and  destroys  the  red 
corpuscles,  causing  the  pale  skin  of  a  person  suffering 
from  malarial  fever.  It  has  not  been  proved  that 
malarial  fever  comes  in  no  other  way.  It  may  be  possible 
that  this  fever  is  caused  by  the  vapors  that  arise  from 
marshy  places.  It  increases  in  any  region  where  the  trees 
are  felled,  as  their  destruction  interferes  with  the  drainage, 
and  thus  gives  rise  to  ponds  and  marshy  places  where 
mosquitoes  breed.  The  wiggle-tail  takes  about  ten  days  to 
become  a  mosquito.  If  kerosene  is  poured  upon  the  water 
at  shorter  intervals  than  ten  days,  no  mosquitoes  will  hatch. 
Tin  cans,  barrels,  and  hollow  stumps  containing  water, 
furnish  breeding  places  for  mosquitoes  (Fig.  157). 

318.  The  negroes  in  the  Southern  states  seem  to  have 
developed  in  the  blood  an  antitoxin,  which  enables  them  to 
live  in  "  bottom  lands  "  along  rivers.  In  Africa  they  do 


1 84 


ELEMENTS   OF  PHYSIOLOGY 


not  often  have  the  jungle  fever,  so  fatal  to  Europeans  who 
have  not  become  "acclimated"  —  that  is,  whose  blood  has 


FIG.  157.  —  Mosquitoes.    Comparison  of — 


The  Non-malarial  Genus  Culex. 
Palpi  short. 
Wings  not  spotted. 
Legs  sometimes  spotted. 
Position  at  rest,  parallel  to  surface. 

Larva,  or  wiggle-tail,  breathes,  and  rests 
perpendicular  to  surface  of  water. 


The  Malarial  Genus  Anopheles. 

Palpi  long. 

Wings  sometimes  spotted. 

Legs  not  spotted. 

Position  at  rest  with  abdomen  and  hind 
legs  elevated  at  an  angle  to  surface. 

Larva,  or  wiggle-tail,  is  parallel  to  sur- 
face of  water  when  it  breathes. 


The  sucking  tube  and  feelers  are  long  in  both  genera.  The  long  palpi  of  the  malarial  genus 
furnish  an  infallible  sign.  The  palpi  are  found  on  each  side  of  the  sucking  tube.  The 
feelers  are  next  to  the  palpi. 

not  developed  the  antitoxin  which  kills  the  germs  caus- 
ing jungle  fever.  It  has  been  shown  that  the  mosquito 
is  probably  instrumental  in  transmitting  yellow  fever. 

319.    Antitoxin  Treatment.  —  If   the  toxins   from   diph- 
theria germs,  grown  in  suitable  material,  are  injected  into 


HYGIENE   OF  RESPIRATION 


185 


the  veins  of  a  horse,  the  horse's  blood  will  soon  develop 
the  antitoxin  of  the  disease.  If  the  blood  is  drawn  and 
allowed  to  clot,  clear  serum  may  be  separated.  If  this  is 
injected  into  a  person  suffering 
from  diphtheria,  it  tends  to  destroy 
the  germs  and  stop  the  disease. 
It  may  prevent  disease  in  the  case 
of  a  person  who  has  been  exposed 
but  in  whom  the  disease  has  not 
yet  developed.  The  antitoxin  treat- 
ment has  been  tried  without  success 
in  several  other  diseases.  Germs 
may  be  transmitted  by  drinking- 
water,  in  the  food,  Or  through  the  FIG.  158.  — How  to  have  a  Dry 

air.  Cellar- 

320.  Vaccination.  — In  1776  E.  «'dam^ro< 

Jenner  of  Berkeley,  England,  learned  that  the  milkmaids 
of  the  shire  considered  accidental  cowpox,  caught  while 
milking,  a   sure   preventive   of   smallpox.     Twenty  years 
later  he  began  to  vaccinate  with  cowpox 
material  to  prevent  smallpox.     Vaccina- 
tion  protects  only  for  a   few  years.     If 
exposed  to  smallpox,  one  should  be  vac- 
cinated, unless   he  has  been  vaccinated 
within  the  last  few  years.     Arm  to  arm 
FIG.  159. — A  "  Trap  "   vaccination  is  dangerous.  Only  fresh  virus 
of  Water  to  Prevent   from  healthy  cows  should  be  used.    If  the 

Gases  from  coming  ,,  ,     ,. 

into  Houses  through   arm  becomes  very  much  swollen  and  dis- 
Drainage    and   abled,  it  is  a  sign  that  the  blood  has  been 

Sewer  Pipes. 

poisoned  by  the  use  of  impure  material. 

321.  Why  a  Person  can  have  Some  Diseases  only  once. — 

Why  does  not  one  have  measles,  smallpox,  and  some  other 
germ  diseases  a  second  time  ?  It  is  believed  to  be  on  the 
same  principle  that  vaccination  prevents  smallpox  the  first 
time.  After  once  having  a  disease,  the  antitoxin  of  that 


1 86 


ELEMENTS   OF  PHYSIOLOGY 


disease,  or  the  power  of  the  blood  to  develop  it,  remains 
and  affords  protection  from  the  bacteria. 

322.  Destruction  of  Bacteria  outside  of  the  Body.  —  The 
sun  is  the  great  destroyer  of  bacteria  in  summer  and  in 
tropical  climates.  Cold  destroys  them  in  winter  and  in 
cold  climates.  Sternberg  has  shown  that  exposure  to  one 
hour  of  sunshine  destroys  the  bacillus  of  consumption. 
Wind  drives  away  bacteria.  It  is  almost  impossible  to 
transmit  disease  in  the  open  air.  Some  germs  feed  upon 


FIG.   160.  —  Poorly    Drained    and    Un 

healthful  Site  for  House. 

a,  sand;  £,  clay. 


FIG.  161.— Healthful  House. 
a,  sand;  b,  rock. 


other  germs.  In  the  soil  are  certain  kinds  of  germs  which 
oxidize  all  organic  matter,  including  other  kinds  of  germs. 
Thus  germs  can  filter  through  only  a  few  feet  of  sand 
before  they  are  destroyed.  Well  water  is  safe  to  drink  in 
the  country,  if  no  impurities  reach  the  soil  near  the  well, 
but  in  towns  where  the  ground  becomes  soaked  with  germ- 
laden  sewage,  impurities  penetrate  farther  and  well  water 
is  unsafe  (Figs.  162,  163). 

323..  Cleaning  with  soap  and  water  removes  germs.  Dry- 
ing kills  many  germs,  but  some  species  are  harder  to  kill 
when  dry ;  in  that  condition  they  will  stand  even  freezing. 
Heat,  equal  to  that  of  boiling  water,  applied  for  15  min- 
utes, will  kill  almost  every  kind  of  germs.  It  does  no 
harm  to  leave  air  in  the  top  of  canned  vegetables  and  jars 
of  preserves,  but  if  they  are  to  keep  fresh,  the  germs  must 
be  killed  by  a  boiling  temperature.  Milk  is  a  nourishing 


HYGIENE   OF  RESPIRATION 


I87 


soil  for  germs  which  cause  stomach  trouble  with  bottle- 
fed  babies,  unless  the  milk  and  the  bottles  are  subjected  to 
hes  t.  Such  milk  is  said  to  be  sterilized. 

324.    Many  chemicals,  as  carbolic  acid  (if  applied  directly 
to  the  germs),  bichlorid 
of   mercury  (i    part  to 
1000    parts    of    water),  ^. 
chlorid  of  lime,  destroy 
germs    and    are    called 
germicides   ("  germ-kill- 
ers "),     and     antiseptics 
(against   decay).     They 
are  called  also  disinfect- 


ants,   and    are    applied 

to  houses,  clothes,  and 

premises  where  disease 

germs  are  supposed  to 

lurk.      The  room  and  bedding  where  there  has  been  an 

infectious  disease  should  be  thoroughly  disinfected.     Any- 


FIG.  162.  —  Badly  Made  Well  polluted  with 
Sewage. 


thing  without  germs,  as  pure  food,  is  said   to  be  aseptic 

(without  decay). 

325.  Aseptic  Surgery. 
—  Some  years  ago,  when- 
ever a  leg  was  amputated, 
or  other  surgical  opera- 
tions were  performed, 
there  was  the  great  dread 
that  mortification  would 
set  in.  It  caused  death 
in  one  third  of  the  sur- 
gical cases.  Now,  with 
aseptic  surgery,  mortification  and  blood  poisoning  are 
very  rare.  The  surgeon  washes  and  sterilizes  his  hands 
and  instruments  and  his  aprons.  He  scrubs  the  field  of 
operation  on  the  body  just  as  he  does  his  hands.,  The 


FIG.  163.  —  Inappropriate  Neighbors. 


1 88  ELEMENTS   OF  PHYSIOLOGY 

safety  which  has  been  brought  about  by  aseptic  surgery 
depends  upon  excluding  the  germs  of  disease. 

326.  Alkaloids.  —  There    is    another    class   of    organic 
poisons,    closely   related    to  ptomaines,  which  should   be 
mentioned.      They  are  vegetable    and    animal    alkaloids. 
Ptomaines  are  formed  by  bacteria  in  dead  organic  matter ; 
toxins  are  formed  by  bacteria  in  living  bodies.     The  alka- 
loids are  formed  without  bacteria,  but  are  waste  products 
formed  in  living  animals  and  plants  by  their  life  processes. 
Among  vegetable  alkaloids  may  be  mentioned  strychnine 
of  nux  vomica,  daturine  of  the  jimson  weed,  atropine  of 
the  belladonna,  nicotine  of  tobacco,  podophyllin  of  the  may- 
apple  root,  caffeine   of    the  coffee  plant,  quinine  of  the 
Peruvian  bark  or  cinchona  tree,  theobromine  of  coca,  theine 
of  tea,  morphine  of  the  poppy,  etc.      They  form  the  active 
principles  of  most  medicines,  and  are  given  for  either  a 
narcotic  (deadening)  or  a  stimulating  (exciting)  effect. 

327.  The  dangerous  properties  of  most  medicines  cause 
us  to  wonder  why  some  people  experiment  with  them  so 
rashly  without  professional  advice.     Persons  who  would 
not  think  of  playing  the  part  of  a  lawyer,  or  a  theologian, 
or  even  of  trying  to  doctor  a  horse,  if  the  horse  was  of 
much  value,  do  not  hesitate  to  prescribe  the  most  virulent 
remedies  for  their  friends  and  families.      The  course  in 
medical  schools  in  the  United  States  is  now  usually  four 
years  in  length.     Most  of  our  physicians  are  not  mere  pill- 
peddlers  and   prescribers   of   drugs,  but   are   capable   of 
advising  their  patients  in  every  aspect  of   their  physical 
welfare,  and  their  advice  should  be  taken  and  paid  for  as 
readily  as  their  drugs. 

328.  Taken  in  large  doses,  alkaloids  are  virulent  poisons. 
The  chief   animal   alkaloids   are  xanthin,  and  other  com- 
pounds related  to  uric  acid.    Very  little  is  known  about  the 
alkaloids  and  their  properties. 

329.  A  Curious  Theory.  —  There  is  an  artless  theory  com- 


HYGIENE    OF  RESPIRATION  189 

mon  among  unlettered  people  which  holds  that  disease 
is  a  distinct  thing,  and  that  when  God  made  the  various 
diseases,  he  made  plants  to  grow,  each  of  which  contains 
the  infallible  remedy  for  one  of  the  diseases.  Such  per- 
sons when  they  are  ill,  and  after  various  treatments  remain 
ill,  cherish  the  firm  conviction  that  if  they  could  only  find 
the  .right  remedy  that  is  growing  in  some  plant,  somewhere 
in  the  world,  they  would,  immediately  be  cured,  without 
any  attention  to  hygiene  and  the  conditions  necessary  to 
health  and  its  recovery.  Patent  medicine  venders  particu- 
larly foster  this  idea,  although  each  one  illogically  adds 
that  his  medicine  will  cure  all  diseases  indiscriminately. 
They  give  instances  of  the  cat  and  dog  that  get  sick  and 
cease  eating  meat  for  a  time  and  are  said  to  eat  grass. 

330.  This  simple  theory  is  opposed  to  all  the  facts. 
The  poisons  in  plants  are  waste  products  that  the  plant 
seeks  to  remove.  They  are  therefore  found  mostly  in  the 
parts  of  the  plant  that  will  be  shed,  as  the  leaves,  seeds, 
and  bark.  The  poisons  serve  meanwhile  to  protect  the 
plant  from  animals.  The  only  animals  (besides  man)  that 
will  touch  the  tobacco  plant  are  the  goat  and  the  tobacco 
worm;  their  bodies  seem  to  have  become  used  to  the 
poison.  No  sick  cat  eats  nightshade,  no  sick  cow  eats 
jimson  weed.  The  very  bitter  or  repulsive  taste  of  most 
poisons  show  them  to  be  unsuited  to  the  animal  body. 
No  child  would  drink  a  liquid  containing  the  bitter  alkaloid 
caffeine,  unless  it  were  influenced  by  the  example  of  its 
elders,  and  the  bitter  taste  were  disguised  with  milk  and 
sugar. 

APPLIED  PHYSIOLOGY 
EXERCISE  I 

i.  State  how  in  the  case  of  a  person  of  poor  figure,  a  gradual  re- 
molding of  the  cartilages  (which  ones  ?),  the  strengthening  of  the 
muscles  (which  ones  ?),  and  the  practice  of  deep  breathing  may  each 
contribute  toward  acquiring  a  correct  and  perfect  figure. 


190  ELEMENTS   OF  PHYSIOLOGY 

2.  How  far  is  it  in  one's  power  to  determine  the  shape  and  appear- 
ance of  his  own  body  ? 

3.  Which  is  most  disagreeable,  a  smoky  fireplace,  a  smoky  stove, 
or  a  smoky  man  ? 

4.  Give  reasons  why  the  weight  of  our  clothing  should  hang  from 
the  shoulders  and  not  from  the  waist. 

5.  Should  a  hat  be  well  ventilated  ?     (A  punch  for  making  the 
holes  costs  a  dime.) 

6.  Name  habits  that  impair  the  power  of  the  lungs. 

7.  Which  part  of  ordinary  breathing  uses  no  will  power,  although 
none  of  the  respiratory  muscles  are  involuntary  ? 

8.  How  could  you  convince  a  person  that  a  bedroom  should  be  open 
while  and  after  it  is  swept  ?     That  it  should  be  ventilated  at  night  ? 

"9.  Why  do  some  persons  "  get  out  of  breath  "  readily  after  a  meal  ? 

10.  Can  a  person  become  so  used  to  bad  air  that  he  will  not  notice 
it  ?    That  it  will  not  injure  him  ? 

EXERCISE  II 

11.  Which  is  the  more  offensive,  the  tobacco  chewer,  who  chiefly 
pollutes  the  ground,  or  the  smoker,  who  pollutes  the  air  ? 

1 2.  Why  are  those  who  have  pimples  on  the  face  likely  to  multiply 
their  number  by  picking  and  squeezing  them  with  the  fingers  ? 

13.  Give  the  advantages  of  slow,  deep  breathing  as  compared  with 
quick,  shallow  breathing. 

14.  Why  do  those  who  stand  up  to  hoe  not  get  tired  half  so  quickly 
as  those  who  bend  or  "  hump  "  over  ? 

15.  Why  do  students  who  sit  in  rocking-chairs,  or  from  other  causes, 
lean  the  head  forward  when  they  study,  often  find  that  they  recover 
from  drowsiness  if  they  sit  erect  ? 

1 6.  How  are  high  collars  a  fruitful  source  of  bad  colds  ? 

17.  Is  ventilation  easier  in  winter  or  in  summer  ? 

1 8.  How  do  you  account  for  the  fact  that  people  of  general  intelli- 
gence on  most  subjects  sometimes  use  oil  stoves,  which  are  stoves 
without  stovepipes  ? 

19.  If  the  draught  up  the  chimney  of  the  fireplace,  when  the  fire  is 
burning,  takes  up  a  volume  of  air  sufficient  for  many  people,  why  is  it 
unwise  to  open  a  window  ? 

NOTES 

i.   Respiration  in  Consumption.  —  Doctors  Robin  and  Binet  studied 
the  respiration  of  nearly  400  cases  of  consumption,  and  reported  their 


HYGIENE   OF  RESPIRATION  1 91 

results  to  the  Paris  Academy  of  Sciences  (1901).  They  discovered 
that  the  respiratory  changes  become  greater  in  consumptive  patients 
than  in  healthy  persons,  thus  completely  overturning  the  general  belief 
on  the  subject.  The  volume  of  inspired  air  was  nearly  doubled. 

The  investigators  therefore  believe  that  the  old  name  "consumption" 
is  a  good  name  for  the  disease.  To  cure  the  disease,  it  is  not  sufficient 
to  remove  the  bacillus.  The  labored  and  exhausting  breathing  due  to 
abnormal  functional  and  nutritive  trouble  brings  the  lungs  into  a  con- 
dition favorable  to  the  development  of  the  bacillus,  and  these  troubles 
must  first  be  removed. 

2.  The  Cure  of  Consumption.  —  D.  M.  Appel,  major  and  surgeon, 
United  States  Army,  makes  the  following  statement :  — 

"  We  have  demonstrated  at  the  Fort  Bayard  sanitarium  for  soldiers 
that  we  can  cure  consumption  in  any  stage.  I  don't  mean  to  say  that 
if  people  come  to  us  with  lungs  so  far  gone  as  to  destroy  their  breathing 
power  we  can  cure  them,  but  I  do  say  we  can  cure  what  has  long  been 
regarded  as  hopeless  —  the  third  stage  of  the  disease.  The  treatment 
is  merely  that  which  has  been  for  years  followed  by  the  practitioners  of 
the  rational  system.  It  consists  of  open-air  living,  generous  diet,  and 
rest.  During  the  daytime  the  patients  are  not  allowed  under  cover,  and 
at  night  all  windows  are  wide  open.  It  is  a  common  thing  for  these 
patients  to  gain  ten  pounds  a  week.  One  increased  from  140  to  190, 
another  from  128  to  210,  and  another  from  less  than  100  to  160." 

3.  "The  degree  of  vital  activity  of  which  we  are  capable  is  gauged 
exactly  by  the  amount  of  oxygen  we  breathe.     The  bird  which  soars 
above  the  clouds  has  enormous  lungs ;  even  its  hollow  bones  are  util- 
ized for  breathing  purposes  ;  it  may  almost  be  said  that  a  bird  breathes 
to  the  very  tips  of  its  toes.     The  frog,  on  the  other  hand,  has  no  chest, 
has  merely  a  small  breathing  bag,  which  it  fills  at  comparatively  long 
intervals.     Compare  the  activity  of  the  swallow,  easily  keeping  pace 
with  the  lightning  express,  with  that  of  the  frog,  croaking  amid  the 
slime  and  miasma  of  a  stagnant  pool"  (J.  H.  Kellogg,  M.D.). 

4.  "The  Greeks,  whose  figures  remain  everlasting  and  unapproachable 
models  of  human  beauty,  wore  no  stays.     The  first  stays  mentioned 
that  I  have  ever  found,  is  in  the  letters  of  Synesius,  Bishop  of  Cyrene, 
on  the  Greek  coast  of  Africa,  400  A.D.     He  tells  how,  when  he  was 
shipwrecked  on  a  remote  part  of  the  coast,  and  he  and  the  rest  of  the 
passengers  were  starving  on  cockles  and  limpets,  there  was  among  them 
a  slave  girl,  out  of  the  far  East,  who  had  a  pinched,  wasp  waist,  such  as 
you  may  see  on  the  old  Hindu  sculptures  and  such  as  you  may  see  on 
any  street  in  any  British  town.     'And  when  the  Greek  ladies  of  the 
neighborhood  found  her  out,  they  sent  for  her  from  house  to  house  to 


IQ2  ELEMENTS   OF  PHYSIOLOGY 

behold,  with  astonishment  and  laughter,  this  prodigious  waist,  with 
which  it  seemed  to  them  impossible  for  a  human  being  to  breathe, 
or  live  ! ' 

"  In  future  years,  when  mankind  has  learned  to  obey  more  strictly  those 
laws  of  nature  and  science,  which  are  the  laws  of  God,  the  present 
fashion  of  tight  lacing  will  be  looked  back  upon  as  a  contemptible  and 
barbarous  superstition,  denoting  a  very  low  level  of  civilization  in  the 
people  who  have  practiced  it"  (Rev.  Charles  Kingsley). 


CHAPTER   XII 
FOOD 

331.  Proteids,  or  Albuminoids.  —  It  was  learned  in  an 
early  chapter  that  protoplasm,   the   basic   life  substance, 
is  not  always  the  same  in  composition,  but  there  is  one 
material  that  is  always  found  in  it  and  is  the  test  by  which 
it  is  known   to   be  protoplasm,  and   that   is   albuminous 
material.       It  was    learned   in   Chapter  II  that   albumin 
always  contains  nitrogen,  the  most  inert  and  inactive  of  the 
elements,  and  that  albumin  gives  strength  and  stability  to 
the  cells  and  tissues.     The  fibers  of  connective  tissue,  for 
instance,    are    albumin.      It   is   the   great   tissue-building 
material,  and  as  the  activities  of  cell  life  are  constantly 
using  up  the  materials  of  the  cells,  we  are  not  surprised 
that  albuminous  or  nitrogenous  food  is  reckoned  as  the 
most   essential   of    all   foods   for   sustaining   animal   life. 
Albuminous  foods  are  commonly  called  pro'te-ids,  or  pro- 
te-in  foods  (Greek  protos,  first  or  most  important). 

332.  Carbohydrates,  or  Sugars  and  Starches.  —  Why  are 
roasting-ears  sweet,  although  mature  corn  is  not?     It  is 
because  the  sugar  in  the  first  has  been  changed  to  starch 
in  the  second.     On  the  other  hand,  ripe  apples  are  sweet 
because  the  starch  of  green  apples  has  been  changed  to 
sugar.     Starch  and  sugar  are  so  nearly  alike  in  composi- 
tion and  change  so  readily  into  each  other,  that  as  foods 
they  are  classed  together.     It  was  learned  in  Chapter  IX 
that   the  sugar  in  the  blood  -is  diminished  by   muscular 
exertion.     The  oxidation  of  the  sugar  is  accompanied  also 

o  193 


194  ELEMENTS   OF  PHYSIOLOGY 

by  increase  of  the  bodily  heat.  It  was  learned  that  fat 
is  stored  up  in  the  interior  of  cells  (Fig.  38).  Sugar  can 
be  changed  into  fat  by  the  cells  and  stored  away  for  future 
use  in  producing  heat  and  motion.  Thus  sugars  and 
starches,  or  the  carbohydrate  class  of  foods,  have  three  uses. 
Knowing  the  great  importance  of  movement  to  our  life, 
and  also  the  fact  that  the  body  is  constantly  losing  heat, 
day  and  night,  winter  and  summer,  the  importance  of  this 
class  of  foods  is  easily  understood.  Some  animals  and 
plants  have  fat  and  oils  or  liquid  fat  in  their  tissues  .ready 
for  use  as  food  by  man.  This  gives  us  a  third  class 
of  foods,  the  — 

333.  Fats.  —  Fats  are  exactly  the  same  in  function  as 
the  carbohydrates.     A   pound  of   fat   in   oxidizing  gives 
out  two  and  one  half  times  as  much  heat  as  a  pound 
of  sugar  or  starch,  and  about  the  same  as  a   pound  of 
albumin.     It  may  be  stored  up  as  fat  in  the  body  if  not 
oxidized  in  the  muscles  to  promote  heat  and  work.     Under 
all   circumstances,    a    certain   amount   of    nitrogenous   or 
proteid  food  is  required  by  the  muscular  tissue,  for,  as 
in  all  cells,  the    real  living  framework  of  the  muscular 
fibers  contains  albuminous  substances  as  one  of  its  essen- 
tial constituents.     We  may,  then,  think  of  fat  and  sugar 
as  having  the  same  relation  to  the  structural  substance 
of  the  muscle  as  the  coal  has  to  the  structural  parts  of 
the  engine. 

334.  Mineral  Foods.  —  The  food  stuffs  so  far  mentioned 
are  all  organic  substances.     There  are  many  inorganic  or 
mineral  food  stuffs,  such  as  carbonate  of  lime,  phosphate 
of  lime,  iron,  and  sulphur  that  are  necessary  to  the  body, 
yet  we  cannot  get  them  directly  from  mineral  sources. 
The  bones  are  largely  made   of  lime,   and   if  we   could 
assimilate  lime  by  eating  it,  or  drinking  it  in  "  hard  "  water, 
then  the  people  who  live  in  limestone  regions  and  drink 
hard  water  might  all  be  giants.     We  can  get  phosphates 


FOOD  195 

and  carbonates  of  lime  from  wheat  and  other  grains ; 
sulphur  is  contained  in  eggs ;  iron  is  contained  in  grains, 
tomatoes,  and  most  vegetables.  Iron  tonics,  tincture  of 
iron,  etc.,  do  not  contain  iron  in  an  organic  form.  Only 
plants  can  furnish  these  mineral  foods  in  a  form  most 
suitable  for  assimilation  by  our  bodies.  Animals  must 
get  them  from  vegetables,  and  they  may  become  part  of 
the  bodies  of  several  successive  animals  as  one  makes  food 
of  another. 

335.  But  you  may  ask,  how  is  it  that  plants  only  have 
the   power  of   nourishing   themselves  with    mineral    sub- 
stances although  we  take  water  and  common  salt  as  food? 
Are  these  two  exceptions  to  the  rule  ?    It  is  doubtful  whether 
such  substances  can  be  strictly  called  foods,  for  food  must 
undergo  a  chemical  change  in  the  body,  while  water  and 
salt  do  not,  but  are  found  to  leave  the  body  unchanged 
in  the  perspiration  and  other  excretions.     They  serve  only 
a  mechanical  purpose  of  dissolving  the  true  foods  and 
bringing  them  within  the  reach  of  the  cells,  for  it  was 
learned  that  all  the  cells  lead  a  watery  existence.     Nerve 
cells,  as  well  as  others,  are  bathed  in  lymph,  and  it  is  in 
a  manner  true  that  we  even   think  under   water.      The 
mechanical  foods,  are  therefore  of  the  greatest  importance  in 
keeping  the  tissues  in  the  right  condition  for  the  cells  to 
work. 

336.  Table:  — 


FOOD  STUFFS 


f  Proteids  —  Nitrogenous  substances. 
Organic       \  Fats  and  oils  1  Non-nitrogenous 

[  Sugars  and  starches  J       substances. 

\.  Inorganic    !Waten 

I  Salts  (salines). 


The  non-nitrogenous  foods  are  sometimes  called  carbo- 
naceous foods  because  they  contain  a  greater  amount  of 
carbon  than  the  proteids ;  remember,  however,  that  the 
proteids  have  some  carbon. 


196  ELEMENTS   OF  PHYSIOLOGY 

337.  Composition  of  Foods.  —  Very  few  of  the  articles  of 
food  we  eat  consist  of  only  one  of  the  classes  of  foodstuffs 
mentioned ;  most  foods  consist  of  several  foodstuffs  com- 
bined.   Oatmeal,  for  instance,  contains  starch,  a  small  pro- 
portion of  oil,  a  large  proportion  of  proteid,  some  mineral 
salts,    and    water.      Let  us  see  how  the  four  classes  are 
represented  in  milk.      The  part  that  makes  it  liquid  is 
water,  the  sweetness  comes  from  the  sugar,  the  cream  rises 
as  oil,  and  the  curd  will  furnish  cheese,  which  contains 
casein,  a  form  of  proteid. 

338.  Experimental  Tests  of  Starch  and  Proteid. — With 
ten  cents'  worth  of  iodine  from  the  drug  store  the  teacher 
may  try  the  following  experiments  :  —  Dilute  a  part  of  the 
iodine  with  water  to  a  light  brown  color.    Make  a  thin  paste 
by  boiling  laundry  starch  in  water.    Put  some  of  this  paste 
into  an  ordinary  glass  and  pour  a  little  of  the  dilute  iodine 
upon  it.     Notice  that  the  starch  turns  instantly  to  a  beau- 
tiful blue  color.     This  is  one  of   the  chemical  tests  for 
starch,  and  is  called  the  iodine  test. 

339.  Put  a  little  piece  of  lean  meat  into  some  of  the  un- 
diluted iodine ;  the  meat  turns  brown.     This  is  the  iodine 
test  for  proteid. 

340.  Soak  some  grains  of  corn,  wheat,  rye,  and  other 
grains  for  a  few  hours.      Make  thin   slices  across  each 
kernel.     Place  a  slice  of  each  grain  in  a  few  drops  of 
dilute  iodine  in  a  saucer,  and  notice  which  part  turns  blue. 
Put  slices  of  each  grain  into  strong  iodine,  and  after  they 
have  been  acted   on  for   several   minutes,  rinse   off   the 
iodine.     Notice  which  part  is  blue  and  which  parts  are 
brown.     In  the  grain  of  corn,  for  instance,  the  white  part 
of  the  kernel  turns  blue,  showing  the  presence  of  starch, 
while  the  germ  and  the  part  around  it  turn  brown,  show- 
ing the  presence  of  proteid.     The  oil  in  the  corn  is  mixed 
with   the   starch    and    proteid,  and    cannot   be   shown  by 
a  simple  experiment.     If  the  grain  of  corn  is  burned,  a 


FOOD  197 

small    amount   of    ashes   remains,    showing    the   mineral 
matter.     Cereals  contain  all  of  the  four  classes  of  food. 

341.  Sources  of  Food. — All  parts  of  a  plant  may  furnish 
food:  the  seed,  as  the  various  grains,  nuts,  and  fruits  ;  leaves, 
as  lettuce,  cabbage,  dandelion;   roots  and  tubers,  as  pota- 
toes, beets,  turnips,  tapioca  (root  of  cassava) ;  stem,  as  sago 
(pith  of   sago  palm) ;  saps,  as  sugars  (of  cane,  beets,  and 
maple  tree);   honey;  and  oils  (from  peanuts,  cottonseed, 
olives,  pecans  and  other  nuts). 

342.  Sources  of   proteid :   albumen,  in   white   of   egg ; 
gluten,  the  sticky  or  gluey  part  of  grain  ;  casein,  in  cheese 
and  the  curd  of  milk;    fibrin,  in   the  blood  of  animals; 
myosin,  the  basis  of  lean   meat ;    gelatin,  obtained  from 
bones  and  ligaments  by  boiling  ;  vegetable  casein,  in  beans, 
peas,  and  nuts. 

343.  Sources  of  fats  and  oils :  cream  of  milk,  yolk  of 
egg,  oil  of  nuts,  olives,  cottonseed,  cocoanut,  and  fat  of 
meat. 

344.  Sources  of  starch  :  corn,  wheat,  rice,  oats,  and  other 
grains,  potatoes,  cassava,  arrowroot,  sago  (in  this  country 
the  last  two  are  usually  potato  starch  sold  under  those 
names),  beans,  peas. 

345.  Sources   of   sugar :    sugar   cane,    sorghum,    dates, 
honey  (almost  pure  sugar),  bananas  (20  per  cent),  grapes, 
fruits,  beets,  maple  trees. 

346.  Study    the    table    showing    composition   of    foods 
(§  434).     Which  grain  has  the  least  proteid  ?     Which  has 
the  most  ?  the  most  starch  ?  the  least  ?  the  most  fat  ?  the 
least  ?     What  vegetable  foods  are  rich  in  proteid  ?     In  oil  ? 
Which  food  has  least  nutrition  (contains  most  water  and 
cellulose)  ?     Which  has  most  nutrition  ? 

347.  Experience  has  shown  that  the  diet  best  suited  for 
the  body  must  contain,  besides  water,  one  part  of  nitrog- 
enous food  to  four  parts  of  non-nitrogenous  food.     Which 
of  the  foods  in  the  table  approximate  this  proportion  ? 


IQ8  ELEMENTS   OF  PHYSIOLOGY 

348.  Outline  of  Digestion.  —  The  food  is  made  soluble  in 
the  alimentary  canal  and  is  absorbed  by  the  blood  vessels 
and  lymphatics  in  its  walls.     This  canal  is  about  thirty  feet 
long  (Plate  III)  and  consists  of  — 

(1)  The  mouth,  where  the  food  remains  about  a  minute, 
while  it  is  chewed  and  mixed  with  the  saliva ;  the  saliva 
changes  a  portion  of  the  starch  to  malt  sugar. 

(2)  The  gullet,  a  tube  nine  inches  long,  running  from 
mouth  to  stomach  and  lying  just  in  front  of  the  vertebral 
column. 

(3)  The  stomach,  a  large  pouch  where  the  food  is  stored 
and  from  which  it  passes  in  the  course  of  several  hours, 
having  become  semi-liquid,  and  the  proteids  having  been 
partly  digested  by  the  gastric  juice,  an  acid  secretion  from 
small  glands  in  the  stomach  walls. 

(4)  The  small  intestine,  a  narrow  tube  more  than  twenty 
feet  long,  where  the  fats  are  acted  upon  for  the  first  time, 
and  where  the  starches  and  proteids  are  also  acted  upon,  and 
where,  after  about  ten  hours,  the  digestion  and  absorption  of 
the  three  classes  of  foods  is  completed  (Figs.  175,  177). 

(5)  The  large  intestine,  about  five  feet  long,  where  the 
last  remnant  of  nutriment  is  absorbed  and  the  indigestible 
materials  in  the  food  are  gathered  together  (Plate  IV). 

349.  Water  and  salt  require  no  digestion  preliminary  to 
absorption.     After  the  food  is  digested  and  absorbed  and 
carried  to  the  tissues  by  the  blood  and  lymphatics,  it  must 
be  assimilated,  or  made  into  material  similar  to  the  contents 
of  the  cells,  and  stored  up  for  future  use.     Drugs,  narcotics, 
and  alcohol  are  not  stored  up  in  the  cells,  but,  it  is  believed, 
are  largely  oxidized  in  the  blood  and  lymph,  or  expelled 
from  the  system  unchanged. 

350.  The  Waste  of  the  Body.  —  When  the  foods  are  oxi- 
dized in  the  body,  there  are  several  products  of  oxidation 
called  waste  products.      The  starches  and  sugar,  fats  and 
oils,  when  oxidized,  give  rise  to  water  and  carbon  dioxid. 


FOOD  199 

The  proteids  give  rise  to  urea.  This  is  excreted  by  the  kid- 
neys, and  when  it  is  separated  from  the  kidney  secretion  by 
chemical  means,  it  appears  as  a  white,  crystalline  powder. 
There  are  also  found  in  the  secretion  of  the  kidneys  small 
quantities  of  phosphate  and  sulphate  of  lime,  sodium,  and 
potassium.  Urea  is  a  substance  of  great  importance,  as  it 
is  the  chief  waste  substance  produced  by  the  process  of 
decay  and  growth  in  the  cells  of  the  body.  Carbon  dioxid 
leaves  the  body  through  the  lungs,  and  water  leaves  it 
through  the  lungs,  kidneys,  and  skin. 

351.  How  the  Waste  is  measured.  —  If  a  man  were  to 
live  all  day  in  a  small  chamber  placed  upon  very  deli- 
cate platform  scales,  he  would  find  that  he  lost  weight 
every  second  of  his  existence  except  when  taking  food, 
and  more  rapidly  at  some  times  than  at  others,  the  amount 
of  loss  depending  upon  the  activity  of  his  body.  The 
loss  of  weight  occurs  through  the  excretions  which  the 
man  gives  off.  At  average  temperature  of  the  air  and 
average  activity  of  his  body,  the  day's  loss  to  be  replaced 
by  food  eaten,  water  drunk,  and  air  breathed,  would  be 
about  as  follows  :  — 

From  the  large  intestine     .  5  oz.  excrement. 

From  the  skin 25  oz.  perspiration. 

From  the  kidneys       ...  50  oz.  excretion. 

From  the  lungs      .     .     .     .  35  oz.  carbon  dioxid  and  water. 

Total    .     .     .     .  115  oz. 

The  total  loss  is,  then,  nearly  8  pounds,  three  fourths  of 
which  is  water  (nearly  6  pounds).  The  remainder,  except 
the  5  ounces  of  excrement,  consists  of  those  waste  materials 
(solid  or  gaseous)  which  result  from  the  breaking  down  of 
the  active  living  protoplasm  into  simple  chemical  sub- 
stances, through  the  process  of  oxidation.  This  amounts  to 
2J\  ounces  and  is  apportioned  as  follows :  perspiration,  \ 
ounce  of  salts,  and  a  trace  of  urea ;  the  kidney  secretion, 


200  ELEMENTS   OF  PHYSIOLOGY 

I  ounce  of  salts  and    \\  ounces  of  urea;  the  lungs,  25 
ounces  of  carbon  dioxid  gas. 

352.  Variation  in  the  Amount  of  Food.  —  Suppose  the 
man  in  the  little  room  on  the  scales  were  to  work,  —  for  in- 
stance, turn  a  hand  mill  or  swing  dumb-bells,  —  would  the 
amount  of  waste  be  increased?     Would  the  increase 'be 
chiefly  urea  (from  proteid)  or  carbon  dioxid  (from  carbo- 
naceous food)?     If  it  were  to  turn  very  cold,  the  loss  of 
heat  from  his  body  would  be  greatly  increased,  and  the 
waste  correspondingly  increased.      If   he  were   to  think 
very  hard,  the  increase  would  be  marked.     If  he  were  to 
remain  perfectly  quiet  in  body  and  calm  in  mind,  the  waste 
would  be  decreased ;  likewise,  if  the  temperature  became 
mild.     The  effect  upon  the  waste  would   not  always  be 
perceptible  until  some  hours  after  its  cause,  for  it  takes 
time  for  the  circulation  and  organs  of  excretion  to  remove 
the  waste  after  the  material  of  the  waste  has  been  formed. 

353.  The  Most  Important  Class  of  foods  is  the  proteids. 
They  are  substances  consisting  of  nitrogen,  carbon,  hy- 
drogen, oxygen,  sulphur,  and  phosphorus.      As  sugar  and 
starches,  fats  and  oils,  contain  no  nitrogen,  the  tissues  can- 
not be  built  from  them  alone.     Proteids  not  only  build 
tissue,  but  are  a  source  of  some  heat  and  energy,  so  life 
could  be  sustained  on  this  class  of  foods  alone;  but  it 
would  not  be  the  best  and  healthiest  way  of  living,  because 
in  order  to  get  enough  carbon,  there  would  be  taken  in  an 
excess   of  nitrogen,   and  the  digestive  organs  would   be 
given  extra  work  which  would  be  of  no  value  to  the  body. 

354.  Proportions  of  Nitrogenous  and  Carbonaceous  Food 
needed.  —  The  carbon  dioxid  gas  which  is  daily  lost  by  the 
body  contains  8  ounces  of  carbon,  while  the  urea  which  is 
lost  contains  a  little  more  than  \  ounce  of  nitrogen.     The 
body    thus   loses   carbon   and    nitrogen    in    the    ratio    of 
about  i  to   15.     The  food,  of  course,  must  supply  these 
elements  in  the  same  proportion.      If  one    foodstuff  be 


FOOD  2O I 

taken  in  excess,  part  of  it  will  be  wasted.  If  the  amount 
of  one  foodstuff  absorbed  be  too  little,  the  man  must  con- 
sume part  of  his  body  substances,  and  will  lose  in  weight. 
In  pure  albumin,  such  as  the  white  of  egg,  the  proportion  of 
nitrogen  to  carbon  is  I  to  3  J.  Since  the  proportion  needed 
in  his  body  is  I  to  15,  if  he  eats  enough  white  of  egg  to 
get  just  enough  nitrogen,  he  would  only  get  about  one 
fourth  as  much  carbon  as  he  requires ;  for  the  body  needs 
15  times  as  much  carbon  as  nitrogen  instead  of  3|  times  as 
much.  But  if  he  were  to  eat  enough  of  egg  white  to  get 
the  carbon  required,  he  would  eat  four  times  as  much 
nitrogen  as  the  body  would  use.  If  he  subsisted  on  lean 
meat,  he  would  eat  four  pounds  a  day  to  gain  sufficient  car- 
bon, while  three  fourths  of  a  pound  would  have  supplied 
sufficient  nitrogen. 

355.  A  dog  could  readily  live  on  lean  meat  alone.     If  a 
man  attempted  to  do  so,  the  kidneys  would  have  to  excrete 
the  larger  part  of  the  nitrogen  unused,  and  would  probably 
become  diseased  from  overwork,  if,  indeed,  the  meat  did 
not  become  nauseous  to  the  palate  and  stop  the  experi- 
ment.     Yet,   so    flexible   is    the  human    system,  if   only 
plenty    of    fresh    air    and    exercise   are    taken,    that   the 
Gauchos   (a  tribe  of    Indians  on  the   Pampas   of    South 
America)  live  upon  dried  beef  alone.     But  the  habit  is  a 
strain    upon  the  organs,    and  must   have   been    acquired 
gradually.     They  are  a  very  short-lived  tribe. 

356.  Proteid  contains  carbon   as  well  as  the  carbona- 
ceous foods,  but  not  so  much ;  and  it  is  found  that  proteid 
and  carbonaceous  food  in  the  proportion  of  I  to  4  gives 
the  needed  proportion  of  nitrogen  to  carbon  (i  to  15). 

357.  How  the  Proportion  of  One  to  Four  is  attained.  - 
Since  fat,  starch,  and  sugar  do  not  contain  nitrogen,  it  is 
impossible  to  live  upon  them  alone.     A  dog  fed  only  upon 
carbonaceous  food,  died  in  a  few  days.     Since  these  foods 
contain  plenty  of  carbon,  it  is  obvious  that  by  mixing  them 


202  ELEMENTS   OF  PHYSIOLOGY 

with  proteid,  the  required  proportion  of  nitrogen  to  carbon 
can  be  attained.  In  about  two  pounds  of  bread  there  is 
enough  carbon  for  the  day's  needs,  but  it  gives  only  half 
enough  nitrogen.  So,  by  combining  lean  meat,  cheese, 
beans,  or  nuts  with  bread,  a  sufficiency  of  both  elements  is 
obtained  without  unnecessary  work  or  waste.  With  the 
addition  of  plenty  of  water  and  a  little  salt,  the  diet  is 
chemically  complete. 

358.  How  Different  Peoples  attain  the  Proportion.  —  Milk 
has  an  excess  of  nitrogen,  and  oatmeal  an  excess  of  car- 
bon ;  oatmeal  and  milk  form  a  perfect  food,  and  it  is  not 
surprising  that  a  whole  race  (the  Scotch)  have  lived  upon 
it  and  thrived.     Potatoes  are  mostly  starch  and  water ;  the 
starch  in  them  is  more  than  four  times  as  much  as  the  pro- 
teid, and  an  Irishman  who  tried  to  live  on  potatoes  alone, 
would  have  to  eat  seven  pounds  a  day  to  get  enough  proteid. 
By  eating  milk  and  eggs  also,  he  can  get  along  on  half  the 
amount  of  potatoes  named  above,  and  every  Irish  peasant 
is  said  to  keep  a  cow  and  chickens.     The  Mexicans  eat 
bread  made  of  corn  meal,  and  supply  the  proteid  by  using 
beans  as  a  constant  article  of  diet.     The  Zulus  live  on 
cracked  corn  by  adding  milk  to  it.     The  Arabs  live  on 
barley  and  camels'  milk,  rarely  eating  the  camels'  flesh. 
Hundreds  of  millions  of  people  in  Asia  (the  Hindoos,  Chi- 
nese, and  others)  subsist  mainly  on  rice,  which  is  more 
nearly  pure  starch  than  any  of  the  grains,  containing  only 
6  per  cent  of  proteid,  about  half  as  much  as  wheat  and 
corn ;  the  chief  addition  they  make  is  butter  or  other  fat, 
and  beans,  which  contain  vegetable  proteid.     Their  meagre 
diet  may  partly  account  for  their  lack  of  energy  and  brav- 
ery, and  the  ease  with  which  they  are  conquered  and  con- 
trolled by  European  nations.     The  greatness  of  a  people  is 
largely  dependent  upon  their  diet. 

359.  The  Body's  Method  of  regulating  the  Food.  — We 
should  not  think  that  the  food  eaten  must  be  regulated 


FOOD  2O3 

with  the  greatest  precision.  Any  reasonable  excess  will 
either  pass  through  the  canal  unabsorbed,  or  be  excreted 
from  the  blood,  without  great  injury  to  the  body.  A  want 
of  any  of  the  necessary  elements  will  be  well  tolerated  for 
a  time  until  a  craving  for  a  certain  kind  of  food  will  lead 
later  to  the  supply  of  the  elements  needed.  If  a  person 
feels  bad,  or  the  digestion  seems  weak,  some  will  advise 
dieting.  There  is  a  tendency  among  certain  writers  on 
hygiene  to  overrate  the  importance  of  this  subject.  If 
the  laws  of  health  in  regard  to  fresh  air,  muscular 
exercise,  sleep,  cleanliness,  temperature,  and  the  use  of 
stimulants  be  observed,  our  appetites  will  be  a  suffi- 
cient guide  in  the  matter  of  diet.  These  matters  should 
first  be  looked  to,  and  dieting  then  will  probably  become 
unnecessary. 

360.  It  is  an  instructive  and  important  fact,  that  too 
much  consciousness  of  what  is  eaten  and  too  much  dwell- 
ing on  what  might  be  the  consequence  of  eating  this  food 
or  that  food,  will  bring  about  serious  derangement  of  the 
digestion.  If  we  do  not  abuse  our  tastes,  but  give  the 
proper  heed  to  them,  we  may  keep  a  delicate  indicator 
which  will,  in  a  more  perfect  way  than  any  scientific  table 
has  yet  done,  tell  us  what  is  needed. 

In  this  Chapter  alcohol  and  other  narcotics  have  not 
been  mentioned  as  they  are  not  to  be  classed  as  true  foods. 
Professor  Atwater  recently  found  proof  of  what  has 
always  been  believed  by  physiologists,  namely ;  that  alcohol 
is  oxidized  in  the  body  and  that  it  may  to  a  slight  extent  for 
a  few  days  take  the  place  of  carbohydrates.  Yet  alcohol 
causes  the  lining  of  the  stomach  to  become  unnaturally 
congested,  and  habitual  drinking  causes  it  to  become 
inflamed  and  even  ulcerated.  A  true  food  must  be  capable 
of  nourishing  the  body  without  injuring  it. 


CHAPTER  XIII 

THE  DIGESTION 

361.  The  Digestive  System.  — The  food,  in  order  to  be 
of   service  to  the   body,  must   undergo   several  changes. 
Its  nutritious  portion  must  be  separated  from  the  innutri- 
tious ;    and   the  former  must  be  made  soluble,  or  in  fit 
condition  to  be  taken  up  by  the  blood  and  carried  to  the 
tissues.     This  process  is  called  digestion,  and  the  assem- 
blage of  organs  by  which  it  is  carried  on  is  called  the 
digestive  system.     The  tube  which  forms  the    receptacle 
for   the   food   during   digestion    is  called   the   alimentary 
canal.     In   the  carnivora,  or  flesh-eating  animals,  whose 
food  contains  but  a  small  amount  of  indigestible  matter, 
the  alimentary  canal  is  comparatively  short,  being,  when 
stretched  out,  only  three  or  four  times  the  length  of  the 
body.       In   the   herbivora,    or    grass-eating   animals,    the 
canal  is  thirty  times  the  length  of  the  body.     In  the  hog, 
which  is  omnivorous   ("all-eating"),  it   is   ten   times   the 
length  of  the  body.     If  man's  trunk  only  is  counted,  the 
canal  is  twelve   times  as  long;    if  his  height  is  counted, 
the  canal  is  six  times  as  long. 

362.  The  Alimentary  Canal  has  three  coats  in  its  walls 
throughout  its  whole    length.     What  is  each  for?     The 
inner  coat,  or  lining,  is  a  delicate  epithelial  tissue  called 
the   mucous    membrane.       It   forms    a    smooth   lining   to 
prevent  friction,  and  secretes  a  mucus  which  serves   the 
same  purpose.     The  next  coat  is  the  submucous  coat ;  it 
is    of    elastic    connective   tissue,   and   serves   to   toughen 
and  strengthen  the  wall,  and  to  bind  the  mucous  coat  to 

204 


THE  DIGESTION  2O$ 

the  muscular  coat.  Outside  of  this  is  the  third  coat.  It 
is  composed  of  several  layers  of  involuntary  muscular 
tissue,  which,  by  its  contraction,  causes  the  food  to  move 
along  the  canal  (Fig.  169). 

363.  In  the  walls  of  the  alimentary  canal  are  numerous 
blood  vessels  and  lymphatics?     Opening  on  its  inner  sur- 
face are  mouths  of  ducts  from  the  various  glands  of  the 
digestive  system.     Some  of  the  glands  are  of  considerable 
size  and  lie  outside  of  the  canal ;  others  are  very  minute 
and  are  embedded  in  the  walls  of  the  canal ;  their  secre- 
tions render  the  food  soluble. 

364.  The  Real  Inside  of  the  Body.  —  When  we  swallow 
food  or  drink,  we  are  accustomed  to  say  that  it  is  in  the 
body,    but   anatomically    and   physiologically   this   is   not 
correct.     It  is  on  the  outside   anatomically,  because   the 
mucous  membrane  is  continuous  with  the  skin,  which  is 
the  external  covering.     It  is  on  the  outside  physiologically, 
because  the  food  must  pass   through   the   mucous   mem- 
brane before   it   can    be   assimilated   by   the  tissues   and 
become  of  use  to  the  body.     In  many  kinds  of  sickness 
the  secretion  of  the  digestive  fluids  diminishes  or  ceases 
altogether,  and  persons  sometimes  make  a  sad  mistake  in 
thinking  they  are  giving  food  to  the   patient,  when  the 
food  is  only  irritating  the  alimentary  canal  and  ferment- 
ing or  decomposing,  and  never  really  getting  inside  of  the 
body.     A  lean  person  often  eats  a  great  deal,  expecting 
to  get  fat,  and  finds  that  although  he  has  swallowed  the 
food,  the  nourishment  has  never  really  entered  his  body. 
Many  a  dyspeptic  is  tortured  with  the  gnawings  of  hunger 
yet  is  continually  eating,  and  is  hungry  still,  because  he 
does  not  really  get  the  food. 

365.  The  Mouth.  —  The  food  is  held  in  the  mouth  for 
a  short  time  while  it  is  mixed  with   the  watery  alkaline 
fluid  called  the  saliva,  and  is  ground  up  fine  by  the  teeth. 
The  partition  between  the  nose  and  the  mouth  is  formed 


206  ELEMENTS   OF  PHYSIOLOGY 

by  the  palate  bones,  covered  with  mucous  membrane. 
The  larger  part  of  the  roof  of  the  mouth  is  formed  by 
these  bones  and  is  called  the  hard  palate.  The  roof  is 
completed  in  the  rear  by  the  fleshy  soft  palate.  The  floor 
of  the  mouth  is  occupied  mostly  by  the  tongue ;  the  lips 
form  the  front  wall,  and  the  "cheeks  the  side  walls.  The 
cheek  is  composed  partly  of  a  large  flat  muscle  called 
the  buccinator  ("trumpeter,"  because  used  in  blowing  a 
trumpet).  The  contraction  of  the  trumpeter  muscles,  to- 
gether with  the  movements  of  that  flat  muscle  called  the 
tongue,  keeps  the  food  between  the  teeth  in  the  act  of 
chewing,  or  mastication. 

366.  Salivary  Glands.  —  There  are  three  pairs  of  glands 
that  secrete  saliva.     In  structure  one  of  these  glands  with 
its  duct  resembles  a  minute  bunch  of  grapes  with  a  hollow 
stem.     The  largest,  called  the  parotid,  is  just  beneath  the 
skin  in  front  of  the  ear.     Its  duct  opens  into  the  mouth 
in  the  upper  jaw  opposite  the  second  molar  tooth.     This 
gland  swells  in  a  disease  called  the  mumps.     The  next 
largest  gland  is  the  submaxillary ',  lying  within  the  angle 
of  the  lower  jaw.     Its  duct  opens  into  the  floor  of  the 
mouth.     The  smallest,  the  sublingual,  lies  farther  to  the 
front ;  both  glands  of  the  pair  lie  beneath  the  tongue,  and 
open  by  a  number  of  ducts.     The  fluid  produced  by  these 
glands  becomes  mixed  with  the  mucus  from  the  mucous 
membrane  of  the  mouth  and  is  called  the  saliva. 

367.  Saliva.  —  This  is  a  thin,  colorless,  alkaline  liquid, 
slightly  sticky,  and  often  containing  air  bubbles.     About 
TTMnf  Part  °f  the  saliva  is  a  white  substance  called  ptyalin, 
which  has  the  power  to  change  starch  to  malt  sugar  while 
remaining  unchanged  itself.     Hence  ptyalin  is  a  ferment. 
Ferment  is  the  name  given  to  certain  organic  substances 
which  act  chemically  upon  other  substances,  and  change 
their  nature  without  becoming  changed  themselves.    From 
one  to  three  pints  of  saliva  are  produced  daily.     Its  flow 


THE  DIGESTION 


207 


is  excited  by  the  act  of  chewing  and  by  anything  held 
in  the  mouth,  especially  if  it  be  of  an  agreeable  taste  or 
odor.  Hunger,  or  the  sight  or  thought  of  agreeable  food, 
makes  the  mouth  water  by  stimulating  the  cells  in  the 
glands  to  activity  by  means  of  the  nerves.  But  by  far 
the  most  powerful  of  all  the  excitants  to  the  salivary  flow 
is  dryness  of  the  food.  Only  one  fourth  as  much  saliva  is 
deposited  in  the  same  length  of  time  when  eating  oatmeal 
and  milk  as  when  eating  crackers  or  dry  toast  (Fig.  164). 


B 


FIG.  164.  —  Cells  of  the  Salivary  Gland. 

At  after  rest;  B,  after  a  short  period  of  activity;   C,  after  a  prolonged  period  of  activity. 
Shriveling  and  loss  of  granules  occur. 


I.  Absorption,  or  the  passage  of  digested  food  into  the 
blood  vessels,  is  an  important  sequel  of  the  digestive  pro- 
cess. A  little  of  the  water  containing  sugar  and  salts  is  ab- 
sorbed from  the  mouth  directly  into  the  blood  vessels. 
Poisonous  substances  may  sometimes  be  absorbed  from  the 
mouth  in  sufficient  quantities  to  produce  death.  If  a  drop 
or  two  of  prussic  acid  be  placed  on  the  tongue  or  on  the 
mucous  membrane,  death  occurs  in  a  few  minutes, 
although  not  a  particle  of  it  has  reached  the  stomach. 
Boys  who  take  their  first  chew  of  tobacco  learn  in  a  dis- 
agreeable way  that  the  entire  body  may  be  affected  by 
absorption  from  the  mouth.  The  absorption  in  the  mouth 
is  insignificant  in  amount  compared  to  the  absorption  that 
takes  place  in  the  small  intestine. 

369.    The    Pharynx   (far-inks),   a   muscular   bag   ODen- 
ing  from  the  nose  and  mouth,  is  four  and  a  half  inches 


208 


ELEMENTS   OF  PHYSIOLOGY 


in  length  and  lies  against  the  spinal  column.  It  is 
commonly  called  the  throat.  There  is  an  air  passage 
from  nose  to  lungs  and  a  food  passage  from  mouth  to 
stomach.  They  cross  each  other,  and  the  intersection  is 
called  the  pharynx.  There  are  seven  openings  from  the 

pharynx :  one  to  the  mouth, 
one  below  the  mouth  into  the 
trachea,  one  behind  the  trachea 
into  the  gullet,  and  two  pairs  of 
openings  in  the  upper  pharynx ; 
one  of  these  pairs  is  to  the 
nasal  passages,  and  the  other 
pair  is  into  the  Eustachian 
tubes,  which  lead  to  the  ears. 
When  swallowing,  all  of  the 
openings  close  but  the  one  to 
the  mouth  and  the  one  to  the 
gullet  (see  Plate  VII). 

370.  The  upper  part  of  the 
pharynx,  and  thus  the  openings 
to  the  nose  and  ears,  can  be 
closed  by  raising  the  tip  of  the 
soft  palate,  or  uvula,  against 
the  spinal  column  (Fig.  i6O. 

FIG.  165.  —  The   Mouth  wide   open 

to  show  the  Tongue  and  Palate.      Sudden    laughter  or   coughing 

Uv,  uvula;    Tn,  tonsils;    C.p.,  taste  pa-  while      Swallowing     may      CaUSC 

pillae;    F.p.t   taste    papillae.      On  the  ,                e              .                                                j 

right  side,  branches  of  the  fifth  nerve  the     Soft     palate     tO      relax,     and 

ninth   to  the  then    a    portion    Qf    the    food    Or 

drink  is  sometimes  forced  into 
the  nose.  The  opening  to  the  windpipe  can  be  closed 
in  three  ways:  by  the  vocal  cords  approaching  one 
another ;  or  by  the  descent  of  the  epiglottis,  the  carti- 
laginous lid  of  the  larynx ;  or  third,  by  the  tongue 
arching  itself  back  over  the  windpipe.  The  opening 
from  the  mouth,  called  the  fauces,  can  be  closed  by  the 


THE  DIGESTION'  2OQ 

contraction  of  upright  muscles,  called  the  pillars  of  the 
fauces,  which  connect  the  posterior  part  of  the  soft  pal- 
ate and  the  base  of  the  tongue.  These  muscles  come  to- 
gether in  the  middle  like  sliding  doors.  There  are  two  of 
them  on  each  side,  and  the  tonsils  lie  between  them.  The 
tip  of  the  soft  palate  hangs  down  between  the  pillars, 
and  is  called  the  uvula.  By  looking  into  a  mirror  with 
the  mouth  very  wide  open  and  the  tongue  flattened,  you 
can  see  the  palates,  the  pillars,  the  uvula,  and  perhaps  the 
tonsils. 

371.  The   Tonsils   ( Fig.  165 )   resemble   the   lymphatic 
glands.     They  are  oval  in  shape,  and  lymph  cells,  resem- 
bling white  blood  corpuscles,  are  formed  in  them  by  mul- 
tiplication, and  pass  out  of  the  tonsils  into  the  saliva  as 
salivary  corpuscles.     They  are  supposed  to  be  germicidal 
and  protective.     Sometimes  the  tonsils  swell,  and  by  press- 
ing the  soft  palate  backward  and  upward,  cut  off  the  pas- 
sage  from   the   upper    pharynx   and   nose,    necessitating 
mouth  breathing.     They  are  often   partly  or  entirely  re- 
moved by  the  surgeon  without  noticeable  injury  to  the 
health. 

372.  The  use  of  tobacco  is  a  common  cause  of  diseases  ' 
of  the  throat.     It   causes  a   dryness  and  thirst,  and  fre- 
quently leads  those  who  use  it  to    take  alcoholic  drinks. 
Often  the  habit  of  smoking  produces  a  troublesome  disease 
called  smokers  sore  throat,  which  can  be  cured  only  after 
smoking  has  been   discontinued.     The    heat  of    smoking 
is  very  trying  to  the  organs,  although  not  so  injurious  to 
them  as  the  poison  of  the  tobacco.     A  still  more  dreadful 
disease  which  can  be  traced  to  the  same  cause  is  that  of 
tobacco  cancer.     Persons  dying  of  tobacco  cancer  lose  their 
voices  in  the  advanced  stage  of  the  disease.     This  disease 
is  practically  incurable. 

373.  The  Esophagus,  or  gullet  (Fig.  166),  opens  from  the 
lower   part   of    the    pharynx.      It   is  about    nine    inches 

p 


2IO 


ELEMENTS   OF  PHYSIOLOGY 


long,  and  lies  along  the  spinal  column  behind  the  trachea. 
It  has  the  three  layers  found  elsewhere  in  the  alimentary 
canal,  and  its  walls  are  soft  and  lie  collapsed  when  no 
food  or  drink  is  passing.  The  food  is  under  reflex  con- 
trol after  passing  the  fauces. 
The  contraction  of  the  pharynx 
presses  the  food  down  into  the 
esophagus.  A  ring  of  the  mus- 
cular tube  contracts  just  above 
the  morsel.  This  contraction 
runs  down  to  the  stomach,  forc- 
ing the  food  before  it  as  if  a  tight 
ring  were  slipped  down  over  the 
esophagus.  A  contraction  of  any 
part  of  the  alimentary  canal  in 
this  manner,  as  if  a  wave  were 
traveling  along,  is  called  peri- 
stalsis. While  a  horse  is  drink- 
ing, the  peristaltic  waves  of  the 
esophagus  may  be  plainly  seen 
along  the  neck  (Plate  VII). 

374.    The  Stomach.  —  The  gul- 
let pierces  the  diaphragm  to  the 
left  of  the  center   and   enlarges 
vii).  into  a  pouch  called  the  stomach. 

a,  vertebral  column;    b,  esophagus;     -j^g     or^an     ljes     just    under    the 
c,  trachea;  d,  larynx;  e,  epiglottis;  J 

/,  soft  palate  and  uvula;  g,  open-  diaphragm,    mostly    on    the    left 

ing  of  left  Eustachian  tube;  h,  open-  ,.  J      t,     ir 

ing  of  left  lachrymal  duct;  *',  hyoid  side    of   the   abdomen   and    hall 
L°,n«,  base°of skuiii  ^A^e  covered   by    the   lower  ribs.     It 

scroll-like,  or  turbinated  bones.  Jg    capable    of    holding   about    tWO 

quarts.  When  full,  it  is  about  a  foot  long  and  five  inches 
broad.  Its  shape  is  not  easily  described  (Fig.  167).  It  is 
placed  across  the  abdomen,  and  its  left  end  is  the  larger. 
Its  outline  is  curved  inward  above  and  outward  below. 
When  empty,  it  flattens  and  its  walls  touch,  and  the 


THE  DIGESTION 


211 


mucous  lining  then  lies  in  deep  wrinkles  or  folds.  The 
opening  where  the  gullet  ends  and  through  which  the  food 
enters,  is  called  the  cardiac  orifice  because  it  is  near  the 
heart.  The  opening  where  the  intestines  begin  and 
through  which  the  food  leaves,  is  called  the  pyloric  orifice ; 
both  openings  can  be 
closed  by  circular  mus- 
cles in  their  walls. 

375.  Peritoneum. — 
The  abdominal  cavity, 
or  the  portion  of  the 
large  cavity  of  the  trunk 
below  the  diaphragm, 
has,  like  the  thoracic 
cavity,  a  lining  to  pre- 
vent friction.  This 
membranous  lining  is 
called  the  peritonfaim, 
and  like  the  pleura,  it  is 
double.  It  comes 
the  wall  of  the 
all  around,  lining  it  like 
a  thin  sheet,  until  it 

reaches  the  place  under  the  diaphragm  where  the  gullet 
and  larger  blood  vessels  (aorta  and  vena  cava)  enter,  where 
it  is  reflected  and  courses  downward,  enveloping  the 
stomach  and  other  digestive  organs.  It  penetrates  be- 
tween them  by  means  of  foldings  and  turnings,  thus 
assisting  to  hold  them  in  place.  The  largest  fold  of  all 
is  called  the  great  omentum  and  surrounds  the  small 
intestine.  It  is  fan-shaped  and  its  contracted  part  is 
attached  to  the  spinal  column  for  a  firm  support.  The 
alimentary  canal,  beginning  with  the  stomach,  may  be 
said,  therefore,  to  have  a  fourth  layer,  or  covering,  the 
peritoneum. 


FIG.  167.  —  The  Stomach  laid  open. 

Up  a,  esophagus;  b,  cardiac  dilatation  on  left  side  of 
stomach;  c,  the  upper  wall;  d,  the  pylorus;  e,  bile 
duct.  ^  gall  bladder;  g,  pancreatic  duct,  opening 
with  bile  duct  into  h, :',  duodenum  (see  Plate  V). 


212 


ELEMENTS  OF  PHYSIOLOGY 


376.  The  Peristalsis  of  the  Stomach.— Anything  taken 
into  the  stomach  causes  wavelike  contractions  in  its  mus- 
cular walls.  The  food  is  caused  to  go  from  the  gullet  to 
the  left  of  the  cardiac  orifice,  then  down  to  the  right  and 
back  again,  the  circuit  from  left  to  right,  then  from  right  to 
left,  taking  from  one  to  three  minutes,  according  to  the 

activity  of  the  peristalsis.  The 
muscular  fibers  in  the  walls  of  the 
stomach  are  in  three  layers  (Fig. 
169);  one  layer  runs  lengthwise, 
another  around,  and  the  third 
obliquely,  so  that  the  varied  con- 
tractions cause  the  food  to  become 
thoroughly  mixed  with  the  — 

377.  Gastric  Juice.  — This  is  a 
yellowish  fluid  and  consists  of 
water,  having  in  solution  hydro- 
chloric acid  and  two  ferments. 
These  remarkable  substances, 
although  existing  in  very  small 
quantities,  are  able  to  change  the 
composition  of  large  quantities  of 
food.  In  times  of  rest,  when  there 
is  no  food  present,  the  mucous  mem- 
brane of  the  stomach  is  of  a  pale 
red  color.  But  when  food  is  intro- 
duced, a  change  at  once  takes 
place.  The  membrane  becomes 

charged  with  blood  and  consequently  turns  to  a  deep  red 
color.  The  gastric  juice,  secreted  by  many  small  glands 
(Fig.  168),  appears  on  the  walls  of  the  stomach,  and  peri- 
staltic action  begins  (Fig.  169). 

378.  The  ferment  of  the  gastric  juice  called  rennin  acts 
by  coagulating  milk,  a  change  somewhat  like  the  coagula- 
tion of  the  blood.  It  causes  coagulation  by  acting  upon 


FIG.   168.  —  Three   Glands  of 
the  Stomach. 

t,  epithelium  at  inner  surface  of 
stomach;  m,  mouth  of  gland; 
/,  principal  cells  of  gland;  ov, 
ovoid  cells;  c,  connective  tissue 
below  and  between  the  glands. 


^r'TJfff  DIGESTION 


213 


the  proteid  part  of  the  milk.  It  is  especially  abundant 
in  childhood.  The  other  ferment,  called  pepsin,  softens  the 
proteid  part  of  food  and  reduces  it  to  peptone,  in  which 
form  it  is  soluble  in  water.  Pepsin,  however,  can  act  only 
when  the  hydrochloric  acid  has  accumulated  to  an 
amount  sufficient  to  neutralize  the  alkaline  condition  caused 
by  the  saliva.  This  usually  requires  about  thirty  or  forty 
minutes.  The  hydro- 
chloric acid,  by  its 
presence  in  sufficient 
quantity,  not  only  en- 
ables the  pepsin  to  act, 
but  also  prevents  fer- 
mentation of  the  food 
and  kills  all  germs  that 
may  enter  the  stomach. 

379.  The  saliva  con- 
tinues its  work  even  in 
the  stomach  until  neu- 
tralized   by    the    acid. 
The  pepsin  then  begins 
to  act.     The  outside  of 
the    food    particles    is 
acted    upon    first,    and 
this    digested    part    is 

then  rubbed  off  by  the  peristaltic  movements,  and  the 
next  layer  is  acted  upon.  Its  action  is  confined  to  the 
proteids.  In  fat  meat  the  albuminous  walls  of  the  cells 
are  eaten  away  and  the  fat  is  set  free  but  not  digested. 
Starch  may  also  be  set  free  from  albuminous  envelopes. 

380.  The  food  is  thus  reduced  to  a  semi-fluid  condition 
and  is  called  chyme.      A  slight  absorption  may  take  place 
in  the  stomach,  of  a  portion  of  the  proteids  digested  there. 
Some  of  the  sugar  resulting  from  the  salivary  digestion  of 
starch  by  the  saliva,  may  also  be  absorbed.     Nearly  all  the 


FIG.  169.  —  A  Section  through  the  Walls  of  the 
Stomach.     Magnified  only  15  diameters. 

i,  surface  of  the  mucous  membrane,  showing  the 
openings  of  the  gastric  glands;  2,  mucous  mem- 
brane, composed  almost  entirely  of  glands;  3,  sub- 
mucous  or  areolar  tissue;  4,  transverse  muscular 
fibers;  5,  longitudinal  muscular  fibers;  6,  perito- 
neal coat. 


214  ELEMENTS   OF  PHYSIOLOGY 

absorption  of  the  food  takes  place  in  the  small  intestine, 
and  it  is  there  likewise  that  most  of  the  digestion  takes 
place ;  for,  upon  leaving  the  stomach,  the  greater  part  of 
the  proteids,  sugars,  and  starches,  and  all  the  fats  and  oils, 
remain  to  be  acted  upon. 

381.  After  the  food  has  been  reduced  to  chyme,  the 
pyloric  orifice  opens  every  minute  or  two,  permitting  a  little 
of  the  chyme  to  escape  into  the  intestine.  But  if  some 
hard  object,  as  a  button,  or  a  lump  of  raw  starch  from 
an  unripe  apple  insufficiently  masticated,  enters  the 
stomach,  the  pylorus,  after  a  while,  will  become  fatigued 
and  will  relax  and  allow  it  to  pass  without 
becoming  semi-fluid  (Fig.  170). 

382.  It  is  a  common  notion  that  digestion 
is  carried  on  chiefly  in  the  stomach.  Some 
physiologists  give  tables  stating  that  pork 
requires  five  hours  for  digestion,  fried  beef 
four  hours,  roasted  beef  three  hours,  apples 
FIG.  170.  —  Pylorus,  one  hour,  etc. ;  what  is  meant  is  that  it 
/,  pyloric  sphincter,  requires  that  length  of  time  for  these 

d,  stomach. 

foods  to  leave  the  stomach,  the  digestion 
being1  far  from  complete.  The  tendency  of  investigation 
in  the  last  few  years  is  to  show  that  the  stomach  is  a  kind 
of  storeroom  or  antechamber  which  enables  us  to  eat  food 
in  a  shorter  time,  and  in  which  it  is  stored,  being  softened 
and  kept  free  from  germs  in  the  meanwhile,  that  it  may  be 
delivered  gradually  to  the  intestine.  There  were  four  per- 
sons in  the  world  in  the  year  1900  without  stomachs  (this 
organ  having  been  removed  by  surgeons  on  account  of 
cancerous  or  other  incurable  conditions),  and  the  small 
intestine  joined  to  the  esophagus.  These  persons  had  to 
eat  very  slowly,  taking  their  food  in  a  semi-fluid  condition. 
383.  Retrospect. — Of  the  thirty  or  more  feet  of  the  ali- 
mentary canal,  the  food,  upon  leaving  the  stomach,  has 
traversed  about  two  feet.  Of  the  fourteen  hours  required 


THE  DIGESTION  21$ 

for  digestion,  about  three  or  four  hours  have  passed.  A 
portion  of  the  starch  and  proteid  has  been  digested  and 
a  small  amount  of  each  absorbed  by  the  blood  vessels. 
The  fats  have  not  yet  been  acted  upon. 

384.  It   is   essential   that   the  part  performed  by  each 
prior  organ  should  be  well  performed,  for  this  determines 
whether  the  changes  in  the  food  in  the  next  organ  shall 
be  easily  and  completely  accomplished.      If  the  food  is 
thoroughly  masticated  in  the  mouth  and  the  saliva  well 
mixed  with  it,  this  alkaline  condition  excites  the  flow  of  the 
acid  gastric  juice,  which  otherwise  would  be  scanty.     If 
the  gastric  juice  is  strong  and  acts  freely  upon  the  food,  the 
acidity  of  the  food  as  it  leaves  the  stomach  and  enters 
the  small  intestine,  excites  the  flow  of  the  alkaline  intes- 
tinal juices. 

385.  THOUGHT  LESSON.     Indigestion. 

I.  A  Fetid  Breath. 

1.  Name  three  causes  of  bad  breath. 

2.  Let  us  investigate  whether  indigestion  could  cause  a 
bad  breath.     In  what  kind  (two  qualities)  of  weather  does 
meat  spoil  the  quickest? 

3.  Suppose  that  meat  or  other  food  is  put  into  a  stomach 
with  its  gastric  glands  exhausted  and  its  muscular  walls 
tired  out,  what  will  be  the  rate  of  digestion,   and  what 
might  happen  to  the  food  ? 

4.  Odorous  contents  of  the  stomach  (e.  g.  onion)  can  be 
taken  by  the  blood  to  the  lungs. 

After  answering  mentally  the  above  points,  write  in  a 
few  words  a  logical  statement  of  how  indigestion  may 
cause  a  bad  breath. 

II.  A  Coated  or  Foul  Tongue. 

1.  When  the  doctor  visits  you,  at  what  does  he  first  look  ? 

2.  What  sometimes  forms  on  old  bread  ? 

3.  Do  you  think  such  a  growth  possible  on  undigested 
food  in  the  stomach  (§  309)? 


216 


ELEMENTS   OF  PHYSIOLOGY 


4.  The  microscope  shows  the  coating  on  the  bread  to  be 
a  vegetable  growth.  If  it  forms  on  the  walls  of  the  stomach, 
it  may  extend  to  what  ? 

III.    Stomach  A  che. 

1.  How  can  you  tell  whether  fruit  preserved  in  a  sealed 
glass  jar  is  spoiling  ? 

2.  What  connection  is  there  between  belching  at  times 
after  eating  too  freely  of  sweet  or  starchy  food  and  the 

observation  above  ? 

3.  Why   does    belching    sometimes 
give  relief  to  an  uneasy  stomach  ? 

4.  Can  you,  by  using  these  facts,  ex- 
plain a  cause  of  stomach  ache  ? 

Be  ready  to  give  logical  explanation 
in  class,  of  cause  of  bad  breath,  furred 
tongue,  and  stomach  ache. 

386.  The  Small  Intestine.  —  When 
the  chyme  passes  the  pylorus,  it  enters 
the  small  intestine,  which  is  a  tube 
about  as  large  around  as  the  thumb, 
and  about  thirty  feet  long,  lying  coiled 
in  the  central  part  of  the  abdominal 
cavity.  The  first  part  of  it,  about  ten 
inches  in  length,  is  called  the  duodenum 
(from  a  word  meaning  twelve,  because 
its  length  is  twelve  fingers'  breadth)  (Fig.  167).  The 
mucous  and  submucous  coats  of  the  small  intestine  are 
wrinkled  by  numerous  folds  which  are  crescent-shaped, 
since  no  single  fold  goes  entirely  around  the  tube  (Fig. 
171).  The  folds  are  so  numerous  that  they  occupy  almost 
the  entire  inner  surface.  The  small  intestine  is  the  chief 
organ  of  absorption  as  well  as  of  digestion,  and  the  ab- 
sorbing surface  is  greatly  increased  by  the  folds.  On  and 
between  the  wrinkles  are  innumerable  tiny  projections  called 
villi  (Fig.  172).  Each  villus  contains  a  loop  of  blood 


FIG.  171.  —  A  Portion  of 
Small  Intestine  cut 
open  to  show  the  Folds 
on  its  Inner  Surface. 


THE  DIGESTION 


217 


•pi. 


vessel  and  a  very  small  lymphatic  called  a  lacteal.  Since 
the  villi  are  so  thickly  placed  as  to  cover  the  entire  mucous 
coat  of  the  intestine  like  the  fibers  in  a  piece  of  velvet, 
the  absorbing  surface  is  enormously  increased. 

The  digestive  fluids  that  enter  the  small  intestine  are  the 
pancreatic  fluid  from 
the  pancreas,  the  bile 
from  the  liver,  and 
the  intestinal  juice 
from  the  small  in- 
testinal glands  (Figs. 
172  and  174). 

387.  The  Pancreas 
and  its  Secretions. — 
The  pancreas,  or 
sweetbread,  is  flat, 
narrow,  and  about  six 
inches  long.  It  lies 
behind  the  stomach, 
and  tapers  toward 
the  left,  ending  above 
the  left  kidney.  Its 
shape  has  been  com- 
pared to  a  dog's 
tongue  and  like  the  FlG>  I72>  ~~ To  show  the  Structure  of  the  Wal1  olf 

the  Small  Intestine. 

root    of    the   tongue,  ,    . 

v,  villi,  and  g,  glands    of    the    mucous    membrane; 

it      bends       downward          c.m.,  circular  muscle  layer;  Im,  longitudinal  muscle 
,  layer:    /,  peritoneum,  or  serous  coat. 

at   its   broader    end, 

where  its  duct  leaves  it  and  joins  the  bile  duct  just  before 
emptying  into  the  duodenum.  Its  internal  structure  re- 
sembles the  salivary  gland,  and  it  is  called  by  the  Germans 
the  abdominal  salivary  gland.  The  amount  of  digestion 
accomplished  in  the  small  intestine  is  greater  than  in  any 
other  division  of  the  canal,  and  the  pancreas  is  the  most 
active  and  powerful  of  all  the  glands.  Its  secretion,  the 


218 


ELEMENTS  OF  PHYSIOLOGY 


pancreatic  juice,  is  alkaline,  and  contains  three  ferments, 
one  of  which  (amylopsin)  is  hardly  to  be  distinguished 
from  the  ptyalin  of  the  saliva,  and  continues  the.  digestion 
of  the  starchy  food ;  another  (trypsin)  has  an  action 
similar  to  pepsin,  and  digests  proteids  ;  while  the  third 
(steapsin)  begins  the  digestion  of  an  important  class  of 

foods,  the  fats,  which  have  not 
heretofore  come  in  contact  with 
a  digestive  fluid  that  could  act 
upon  anything  more  than  the 
proteid  envelopes  of  the  fat  cells 
(see  Plates). 

388.  Digestion  of  Fats.  — Fats 
are  digested  not  by  going  into 
solution,  but  by  the  large  globules 
of  fat  being  broken  into  very 

FIG.    173.  —  Semi-diagrammatic     minute  globules.       Such  globules, 

View  of  Two  Villi  of  the  Small     „         .          .  ..        .,     .  ,          . 

intestine.      Magnified   about   floating  in  a  liquid,  form  what  is 

50  diameters.  called  an  emulsion.     Milk  is  an 

a>  substance  of  the  viiius;  t,  its  epi-   emulsion   of   cream.      It    is    the 

thelium;  c,  a,  the  artery  and  vein, 

with  their  connecting  capillary  net-      Cream    in    SWCCt    milk  which  glVCS 

work  which  envelopes  and  hides  f,      •,     .-\  •>   •.  r  i 

the  lacteal  that  occupies  the  Cen-   it  the  white   appearance,  for  the 

ter  of  the  villus  and  opens  into  a     g^buleS    of    fat     reflectthe    light, 
network  of  lacteal  vessels  at  the  base.      j 

When  it  is  churned  these  minute 

particles  touch  and  adhere,  forming  butter.  Fats  are  not 
acted  on  by  acids,  but  they  are  acted  upon  by  alkaline 
fluids.  The  steapsin  ferment  from  the  pancreas,  aided  by 
the  alkaline  bile  from  the  liver,  emulsifies  the  fats,  and  pre- 
pares them  for  absorption. 

389.  Absorption  of  the  Fats.  —  The  fats  are  absorbed  by 
the  lymphatic  system.  Many  minute  lymphatics  called 
lacteals  (Fig.  173)  are  found  in  the  villi  of  the  intestines, 
and  the  epithelial  cells  of  the  mucous  lining  take  up  the 
fat  and  transmit  it,  slightly  changed,  to  these  lacteals, 
which  unite  one  to  another  and  empty  into  the  thoracic 


THE  DIGESTION 


219 


as  to  show  the  Bile 
Duct  (a)  and  the 
Pancreatic  Duct  (b) 
opening  by  a  Com- 
mon Orifice. 


duct.     Where  does  this  duct  empty  ?      The  fats  are  thus 

taken  into  the  blood  stream. 

390.   The    Intestinal    Glands.  —  Besides   the  two   large 

glands,  the  pancreas  and  liver,  there  are 

a  great  number  of  very  small  glands  (Fig. 

172)    which  furnish  a  digestive    fluid    to 

the  intestine.     The  intestinal  glands  are 

scattered  throughout  the  lining  membrane, 

and    their    secretion   is   called  the  intes- 
tinal juice.     It  is  difficult  to  isolate   and 

to  study  because  of  the  minuteness  of  the 

glands,  and  although  their  functions  are 

not  fully  known,  it  has  been  proven  that 

their  secretion  can  digest  cane  sugar  and 

maltose  and  change  them  into  grape  sugar, 

or  glucose.     If  cane  sugar  is  injected  into 

the   arteries,  it   is   excreted    from   the    body   unchanged. 

This   proves   that   the  body  is  incapable  of  assimilating 

cane  sugar  until  it  is  digested. 
391-  Forms  of  Sugar  and 
Starch.  —  Cane  sugar  is  found 
in  sugar  cane,  sorghum,  and 
sugar  beets.  Milk  sugar  is 
found  in  milk.  Malt  sugar 
is  produced  by  the  action  of 
saliva  upon  starch.  Grape 
sugar  (and  fruit  sugar,  which 
intestine  is  nearly  the  same)  is  the 
sweet  element  in  fruits  and 
honey. 

Malt  sugar,  while  passing 
through  the  mucous  mem- 
brane of  the  intestine,  is  con- 

FIG.  175.— The  Digestive  System.        verted  into  grape  sugar,  and 

in   this   form   it  is  absorbed  into  the  blood.     It  may  be 


— Pancreas 


-V—  Small 


Vermiform    . 
Appendix 


22O 


ELEMENTS   OF  PHYSIOLOGY 


produced  artificially  by  the  action  of  vegetable  diastase, 
which  resembles  ptyalin  or  the  ferment  found  in  saliva. 
Glucose,  produced  artificially  by  boiling  starch  with  dilute 
sulphuric  acid  is  of  the  same  chemical  composition  as 
grape  sugar,  but  the  presence  of  sulphur  and  other  chemi- 
cals interferes  with  its  usefulness  as  a  food. 

Dextrin  is  intermediate  between  starch  and  sugar. 

Starch,  unlike  the  sugars,  is  insoluble  in  cold  water. 

392.   Analysis  of  Digestion.  — 


1 

Part  of  alimen- 
tary canal. 

Glands. 

Secretion. 

Food  acted 
upon. 

2 

Mouth. 

Salivary 
(three). 

Saliva. 

Starch. 

3 

Stomach. 

Gastric  glands. 

Gastric  juice. 

Proteids. 

4 

Small  intestine. 

Liver. 

Bile. 

Fats. 

Pancreas. 

.  Pancreatic 
juice. 

f  Starch.     See 

\  Proteids.  See 

(  Fats.     See 

Intestinal 
glands. 

Intestinal 
juice. 

Cane  sugar. 

5 

Large  intestine. 

Absorption.     Amount  of  diges- 

393.  THOUGHT  LESSON. 

(Answers   to    be    found   by  reference   to   table   called 
"Analysis  of  Digestion.") 

1.  In  which  of  the  digestive  organs  is  only  one  kind 
of  secretion  furnished  from  glands  ? 

2.  In  which  organ  are  three  kinds  of   secretions   fur- 
nished it  by  glands  ? 

3.  Which  classes  of  foods  go  through  the  lymphatics  ? 


THE  DIGESTION 


221 


4.  Which  classes  of  foods  go  through  the  liver  ? 

5.  Which  classes  of   foods   are  digested  in  only  one 
organ  ? 

6.  Which  classes  of  foods  are  digested  in  two  organs  ? 
How  do  the  facts  given  in  the  table  show  — 

7.  That  the  pancreatic  juice  is  the  most  important  of 
the  digestive  secretions  ? 

8.  That  bread  needs  to  be  kept  in  the  mouth  for  a 
longer  time  than  lean  meat. 


What  it  is 
changed  to. 

How  it  gets 
into  the  blood. 

What  it  will  be 
used  for. 

Final  product 
of  oxidation. 

1 

Sugar. 

Capillaries  of 
portal  vein. 

Work,  heat, 
and  fat. 

Carbon  dioxid 
and  water. 

2 

Peptones. 

Ditto. 

Building  tissue. 

Chiefly  urea. 

3 

Emulsion. 

Lacteals  of  lym- 
phatic system. 

Heat,  work, 
and  fat. 

Carbon  dioxid 
and  water. 

4 

second  line. 

third  line. 

fourth  line. 

See  second  line. 

tion  here  is  insignificant. 

5 

9.  That  lean  meat  (a  form  of  proteid)  fried  so  that  the 
grease  soaks  into  it,  is  hard  to  digest?  (Suggestion: 
Where  is  fat  digested?  Where  should  the  digestion  of 
proteids  begin  ?) 

10.  That  doughnuts,  or  batter-cakes,  or  any  starchy  food 
cooked  so  as  to  become  grease-soaked,  are  hard  to  digest. 

394.  How  the  Food  gets  into  the  Tissues.  —The  absorp- 
tion of  the  emulsified  fats  by  the  lymphatics  has  been 


222 


ELEMENTS   OF  PHYSIOLOGY 


described.  The  digested  starch  (glucose)  and  digested  cane 
sugar  (glucose)  and  the  digested  proteids  (peptones)  pass 
into  loops  of  the  blood  vessels  contained  in  the  tiny  projec- 
tions called  villi,  and  are  carried  to  the  liver.  Both  the 
small  amount  of  these  substances  which  is  absorbed  by 
the  stomach,  and  the  large  amount  which  is  absorbed 
from  the  small  intestine,  are  taken  by  means  of  a  system 
of  veins  called  the  portal  circulation  (Fig.  178),  to  the 
liver,  where  they  may  be  stored  or  may  pass  through 
the  liver  and  vena  cava  to  the  general  circulation.  The 
mineral  substances,  iron,  lime,  sulphur,  and  phosphates  are 
contained  in  the  proteid  food  and  are  digested  and  ab- 
sorbed with  it.  Water  and  salt  do  not  require  digestion. 
It  was  formerly  believed  that  the  food 
passes  into  the  lacteals  and  capillaries 
strictly  according  to  the  physical  law  of 
osmosis  which  governs  the  passage  of 
fluids  through  dead  membranes.  It  is 
now  believed  that  the  epithelial  cells  lin- 
,  ing  the  canal  take  up  the  food  and  give  it 
into  the  absorbent  vessels  by  a  process 
resembling  secretion ;  but  osmosis  aids 

FIG.  176. -The  Valve     the  PrOCCSS. 

between  the   Large       395.   The    Large    Intestine    or    Colon 

and  Small  Intestine.     (p.  ^    {&   ^^    fiye    ^    1()ng        ^ 

a,  small  intestine;  e,  large 

intestine;  d,  c,  valve;    walls  are  drawn  into  pouches,  or  puckers, 
6,  appendix.  ^y  bands  of  muscles  running  lengthwise 

along  it.  The  small  intestine  joins  it  in  the  lower  part  of 
the  abdomen  on  the  right  side  (Fig.  176).  The  junction  is 
not  at  the  end  of  the  large  intestine  but  above  the  end. 
The  part  below  the  junction  is  called  the  c&cum.  Attached 
to  the  ccecum  is  a  small  tube  called  the  vermiform  appendix. 
Above  the  juncture  the  large  intestine  is  called  the  colon.. 
The  ascending  colon  runs  up  along  the  right  side  nearly 
to  the  waist.  It  is  then  called  the  transverse  colon,  and  it 


THE  DIGESTION 


223 


Acol 


comes  forward  and  crosses  just  in  front  of  the  lower  line  of 
the  stomach.  It  then  retreats  to  the  rear  wall  and  passes 
downward,  being  now  called  the  descending  colon.  Near 
the  left  hip  it  makes  a 
double  bend  called  the 
sigmoid  flexure  (from. 
sigma,  the  Greek  letter 
S).  The  nine  inches  re- 
maining are  without  the 
pouched  appearance, 
the  walls  being  smooth ; 
this  part  is  without 
bends  and  is,  therefore, 
called  the  rectum  (from 
Latin  rectus,  "straight"), 

396.  Absorption      in 
the    large    intestine    is 
very  active  and  its  con- 
tents   soon    lose    their 
fluidity.     Although  it  is 
mostly  the  watery  por- 
tion   that    is    absorbed, 
any  digested  food  that 
may    have  escaped   ab-  FlG 
sorption  in  the  small  in- 
testine,    is     absorbed   by    R*  riSht;  L>  left;  ">  esophagus;  st,  stomach;  Py, 

pylorus;    duo,    duodenum;    ccec,   caecum;    A. col, 

the  COlon.        HOW  Saving        ascending  colon;   T.  col,  transverse  colon;  D.col, 
-,  *  ,-,       ,        i  descending  colon;    R,  rectum. 

and  economical  the  body 

is  !    All  the  undigested  and  indigestible  food  gathers  in  the 

sigmoid  flexure,  and  descends,  at  intervals  into  the  rectum. 

THE  LIVER 

397.  The  Liver  not  merely  a  Digestive  Gland.  — The  liver 
has  three  functions,  (i)  The  bile  secreted  by  it  goes  down 
the  chief  duct  and  "backs  up"  into  the  gall  bladder,  where 


ccec 


verm 


_  The  Alimentary  Canal  in  the 
Abdomen. 


224 


ELEMENTS   OF  PHYSIOLOGY 


it  is  stored  until  food  is  eaten,  when  it  enters  the  alimentary 
canal  and  aids  in  the  digestion  of  the  fats.  (2)  It  serves 
as  a  storeroom  for  digested  food.  You  learned  that  all 
foods  but  the  fats  were  carried  to  the  liver  when  absorbed 

(Fig.  178).  Some  of  them 
are  stored  there  and  given 
out  gradually  as  needed. 
(3)  The  liver  is  an  excretory 
organ.  As  the  blood  contain- 
ing the  food  passes  through 
it,  poisonous  substances  in 
the  blood  from  the  tissues, 
or  poisons  that  may  be  in  the 
food,  are  destroyed  and  the 
products  resulting  from  the  de- 
struction are  sent  out  of  the 
body  by  either  of  two  routes  : 
by  way  of  the  bile  duct  and 
alimentary  canal  or  by  way 
of  the  blood  vessels  and  kid- 
neys. 

As  only  one  of  these  three 
functions  is  strictly  digestive, 
it  is  more  logical  to  treat  the 

carrying  the  Blood  from  the  Viscera    liver     Somewhat     apart     from 

to  the  Liver'  the  digestive  organs. 

398.    Its  Duty  as  a  Guar- 

from  each  other,    /.pancreas;  j/,  spleen;    fa^,  fhe  food  (except  the 

ac,  cd,  large  intestine.      The   transverse 

colon  and  the  small  intestine  have  been  re-    fats)  HlllSt  paSS  the  tCSt  in  the 

liver  before  it  can  reach  the 

system.  All  the  blood  in  the  body  passes  through  it  once 
every  three  or  four  minutes,  and  as  it  passes  it  is  purified. 
The  waste  products  resulting  from  the  work  done  in  the 
body  are  made  more  soluble,  so  that  they  can  be  carried 
through  the  kidneys.  The  yellow  color  of  the  bile  is  due  to  a 


THE  DIGESTION  22$ 

pigment  resulting  from  the  destruction  in  the  liver  of  worn- 
out  red  corpuscles.  The  bile  is  partly  an  excretory  prod- 
uct, but  such  is  the  economy  of  the  system  that  it  serves 
to  aid  digestion,  and  to  keep  the  alimentary  canal  in  an 
aseptic  condition  on  its  way  out  of  the  body.  A  man  could 
not  smoke  were  it  not  for  the  liver.  This  organ  takes  up 
the  nicotine,  if  not  too  great  in  amount,  and  destroys  it. 
If  one  drinks  alcohol,  the  liver  endeavors  to  oxidize  it  and 
get  rid  of  it,  so  that  the  body  may  not  suffer  harm  and  in- 
jury from  it,  and  oftentimes  the  liver  of  a  habitual  drinker 
is  crippled  or  destroyed  by  its  long  struggle  with  alcohol. 

399.  It  has  been  shown  by  experiments  upon  frogs  and 
other  animals  that  twice  as  large  a  dose  of  poison  is  required 
to  kill  an  animal  that  has  a  liver  as  to  kill  one  that  has 
been  deprived  of  this  organ.     Similarly,  it  requires  twice 
as  much  poison  to  kill  a  man  when  it  is  given  through  the 
stomach  and  passes  through  the  liver,  as  when  it  is  injected 
through  the  skin.     Those  who  take  morphine  by  hypoder- 
mic injection  are  more  hopelessly  bound  to  the  habit  than 
those  who  take  it  by  the  mouth. 

400.  A  man  would  live  many  years  longer  than  he  does 
if  he  were  not  all  the  time  producing  waste  products  in  his 
body  by  his  ordinary  activities.     The  excretory  organs  are 
taxed  to  remove  them.     In  the  young  child  as  it  is  growing 
and  developing,  the  skin  is  so  active,  the  kidneys  are  so 
healthy,  and  the  liver  is  so  vigorous,  that  the  waste  is  all 
removed  and  the  blood  is  pure.      That  is  why  a  healthy 
child  has  so  sweet  a  breath,  such  bright  eyes,  and  so  fair  a 
skin.     When  he  becomes  old  it  is  different.     The  same  is 
true  of  a  dog ;  the  puppy's  breath  is  pure,  its  body  is  clean, 
so  that  it  may  lie  in  a  lady's  lap  or  on  a  sofa  and  leave  no 
unpleasant  odor.     But  when  he  is  old,  the  dog  becomes  so 
offensive  that  he  has  to  be  driven  out  of  the  house.     The 
strong  odor  results  from  the  accumulation  of  waste  sub- 
stances in  the  body. 

Q 


226  ELEMENTS   OF  PHYSIOLOGY 

401.  Gross  Anatomy  of  the  Liver.  —  The  liver  is  the  largest 
gland  in  the  body.      It  is  of  a  reddish  brown  color  and 
weighs  about  three  and  one  half  pounds.     The  upper  and 
front  surfaces  of  the  liver  are  very  smooth  and  even.     The 
under  surface  is  very  irregular ;  it  is  here  that  the  various 
vessels  with  which  this  active  organ  is  supplied  make  their 
entrance  or  exit.     It  is  located  under  the  right  portion  of 
the  dome  of  the  diaphragm,  and  its  lower  edge  reaches  a 
little  below  the  border  of  the  thoracic  cage.     (Does  its  left 
end  overlap  the  stomach?     See  Plates.)     Its  connecting 
vessels,  besides  the  lymphatics,  are  the  hepatic  artery  from 
the  aorta,  bringing  pure  blood ;  the  portal  vein,  bringing  the 
digested  food ;  the  hepatic  vein,  carrying  impure  blood  to 
the  vena  cava ;  and  the  bile  duct,  carrying  the  bile  to  the 
intestine.     The  bile  duct,  on  its  way  from  the  liver,  gives 
off  a  side  branch  to  the  gall  bladder.     This  is  a  little  dark 
green  bag,  in  which  the  bile  is  stored  until  it  is  required  for 
digestion  (Plates  III  and  IV). 

402.  With  each  inspiration  the  liver  is  pushed  downward 
and  compressed  by  the  diaphragm,  the  blood  being  forced 
out  toward  the  heart,  and  it  fills  again  as  soon  as  the  breath- 
ing muscles  relax.   This  rhythmic  compression  is  of  great  im- 
portance in  keeping  the  blood  supply  to  the  liver  fresh  and 
pure,  and  preventing  congestion  in  it.     By  tight  clothing 
the  liver  is  often  forced  downward,  out  from  the  cover  of 
the  ribs,  and  becomes  permanently  displaced.    As  a  result, 
other  organs,  lower  in  the  abdomen  and  pelvis,  are  crowded 
upon  each  other  and  also  become  displaced.      The  circula- 
tion in  the  liver  is  diminished,   and  hence  its  activity   is 
decreased  and  the  complexion  loses  its  freshness. 

403.  Circulation  through  the  Liver,  or  Portal  Circulation. — 
The  portal  vein  and  its  function  have  been  mentioned  (Fig. 
1 78  ).    When  it  enters  the  liver,  it  does  a  very  unusual  thing ; 
in  fact,  it  conducts  itself  as  no  other  vein  in  the  body  does, 
except  some  of  the  veins  in  the  kidneys.     It   subdivides 


THE  DIGESTION 


227 


into  capillaries.  Thus  the  portal  vein  (Latin porta,  a  gate, 
since  it  enters  under  a  kind  of  archway)  both  begins  and 
ends  in  capillaries,  for  it  begins  in  the  capillaries  of  the 
digestive  tract  and  ends  in  the  capillaries  of  the  liver.  After 
these  capillaries  have  passed  in  among  the  cells,  they  unite 
again  to  form  the  hepatic  veins,  which  go  directly  to  the 
ascending  vena  cava.  There  is  another  large  blood  vessel 
in  the  portal  circulation.  This  is  the  hepatic  artery,  which 
enters  the  liver  directly  from  the  aorta  and  supplies  the 
liver  cells  with  arte- 
rial blood  with  which 
to  repair  themselves 
and  carry  on  their 
work  (Plate  VII). 
The  capillaries  from 
this  artery  unite  with 
those  of  the  portal 
vein  in  forming  the 

hepatic  Vein.    A  COW'S    FIG.  179.  —  Diagrammatic  Representation  of  Two 
v  .  Hepatic  Lobules. 

liver,    cut     in     two, 

The  left-hand  lobule  is  represented  with  the  intralobular 
vein  cut  across:  in  the  right-hand  one  the  section  takes 
the  course  of  the  intralobular  vein.  /,  interlobular 
branches  of  the  portal  vein;  h,  interlobular  branches 
of  the  hepatic  veins;  s,  sublobular  vein;  c,  capillaries 
of  the  lobules  passing  inwards.  The  arrows  indicate 
the  direction  of  the  course  of  the  blood.  The  liver-cells 
are  represented  in  only  one  part  of  each  lobule. 


shows  in  places  small 
gaping  holes,  which 
are  branches  of  the 
hepatic  veins. 

404.  Minute  Anat- 


omy of  the  Liver.  —  If  you  examine  the  surface  of  a 
piece  of  liver  obtained  from  the  butcher,  you  will  find 
it  to  be  of  a  dark  red  color,  and  mottled  over  with 
little  areas,  each  measuring  about  one  twentieth  of  an 
inch  across.  These  are  the  round  lobules  of  the  liver 
arranged  around  a  branch  of  the  hepatic  vein  (Fig.  1/9). 
The  capillaries  of  the  portal  vein  and  hepatic  artery  and 
the  branches  of  the  bile  duct  pass  between  these  cells. 
Study  carefully  Figure  180,  which  represents  a  segment  of  a 
lobule.  When  you  understand  the  circulation  in  a  lobule, 


228  ELEMENTS   OF  PHYSIOLOGY 

you  will  understand  the  circulation  in  the  entire  liver,  for 
a  lobule  is  the  liver  in  miniature.  Represent  a  lobule  by 
a  wagon  wheel.  The  rim  corresponds  to  the  capillaries 
of  the  portal  vein  and  hepatic  artery  circulating  around  the 
lobule.  The  spokes  correspond  to  the  two  kinds  of  cap- 
illaries united  and  on  the  way  to  the  hepatic  vein  in  the 

hub,  which  will  take  the  blood 
away  from  the  liver.  Between 
the  spokes  are  located  the  hard- 
working liver  cells  which  get 
oxygen  and  food  from  the  capil- 
laries in  the  spokes,  and  relieve 
themselves  of  impurities  by 
means  of  the  finest  bile  ducts 
and  lymphatic  ducts,  which  be- 
gin among  the  cells  (Fig.  181). 
What  are  the  two  large  vessels 
which  bring  material  to  the  liver  ? 

FIG.  !8o.- Microscope,  high  power.    Wfa   t  ^     t          j  vessels 

Diagram  of  a  Portion  of  a  Lobule 

of  the  Liver,  showing  the  Blood  (  besides  the  lymphatics)  which 
wietShS^uidnd  BilC  DUCtS  inJ6Cted  take  material  out  of  the  liver? 

A,  branch  of  portal  vein  sending  capil-  ^'    Th*  LivCT  RS  &  Storeroom. 

larics  to  open  into  E,  a  branch  of  the    If  a  frOg  be  dug  Up  in  the  first 

hepatic  vein  which  lies  in  the  middle  . 

of  the  lobule;    B,  a  lymphatic;    C,  part   of    its  Winter   sleep,  and    itS 

Wver  be  examined  under  the 
microscope,  the  cells  will  be 
found  swollen  and  full  of  gly- 

cogen,  a  substance  stored  up  for  the  winter  needs  of  the 
frog.  It  is  a  carbohydrate  material  resembling  starch  and 
made  from  digested  sugar.  The  liver  cells  of  a  frog  which 
has  just  come  out  in  the  spring  will  be  found  shrunken  and 
containing  no  glycogen  (Fig.  182).  If  a  starving  rabbit  be 
killed  and  its  liver  cells  examined,  no  glycogen  will  be 
found,  but  the  liver  cells  of  a  rabbit  which  has  recently 
been  fed  on  turnips  will  be  full  of  glycogen.  If  two 


THE  DIGESTION 


229 


FIG.  181.  —  Diagram  to  show  the  Termination  of  a 
Fine  Bile  Duct. 

b,  small  bile  duct  becoming  still  finer  at  b' ;  /,  hepatic  cells; 
c,  capillaries  cut  across. 


rabbits  be  well  fed  and  one  kept  in  a  cage  and  the  other 

hunted  around  all  day,  much  glycogen  will  be  found  in 

the  liver  of  the  quiet  rabbit,  and  very  little  in  the  liver 

of  the  hunted  one. 

The  glycogen  stored 

up   is  used   during 

muscular    work    or 

starvation. 

406.    The    sugar 

absorbed     by     the 

small    intestine 

reaches     the     liver 

through  the  portal 

vein.     It    is    taken 

up  by  the  liver  cells 

and    changed    into 

granules   of   glyco- 
gen,  to   be   turned 

into  sugar  again  during  times  of  hunger  and  hard  work. 

Thus  only  a  small  amount  of  sugar  is  allowed  to  enter 

the   circulation   at   one   time,    only    ij    ounces    in   every 

1000  ounces  of  arterial 
blood.  If  more  than  this 
quantity  enters  the  blood, 
sugar  passes  out  through 
the  kidneys,  and  the  func- 
tion of  the  kidneys  may  be- 
come disordered,  a  condi- 
diabetes." 

Urea  is  the  chief 
waste  product  which  results 

from  the  breaking  down  of  proteid,  and  it  is  believed  that 
the  nitrogenous  urea  as  well  as  the  carbohydrate  glycogen 
is  formed  by  the  liver.  An  excess  of  proteid,  such  as 
lean  meat  and  cheese,  in  the  diet,  produces  an  increased 


FIG.  182.  —  Liver  Cells  of  Dog  after  a  Thirty- 
six  Hours' Fast ;  also  Fourteen  Hours  after   tion  known  as 


230  ELEMENTS   OF  PHYSIOLOGY 

excretion  of  urea  through  the  kidneys.  It  is  obvious  that 
excess  of  food  and  lack  of  exercise  may  lead  to  the  chok- 
ing up  of  the  iiver  cells  with  food  products  which  are 
not  required.  This  condition  may  be  relieved  by  a  spare 
diet  and  by  vigorous  exercise.  The  poor,  overworked  liver 
should  not  be  blamed,  however,  nor  the  statement  made 
that  "the  liver  is  not  acting."  At  the  very  time  the  com- 
plaint is  made,  the  skin  and  eyes  may  be  yellow,  showing 
the  presence  of  too  great  a  quantity  of  bile,  which  is  a 
product  of  the  activity  of  the  liver. 

408.  Biliousness  may  result  from  three  causes:  (i)  The 
first  and  most  usual  form  of   biliousness  is  not  bilious- 
ness   at   all,    but    is    caused    by   fermentation    and    other 
forms    of    indigestion,    and    by    the    poisonous    products 
therefrom  entering  the  blood.    (2)  Stoppage  of  the  chief 
bile    duct    because    of    congestion,    which    extends    to    it 
from   the   stomach.     This   congestion   is   caused   by   irri- 
tation  of   undigested   food  (§   597).      (3)  The   liver   cells 
and  ducts  may  become  choked  up   from  excessive  food 

(§  407). 

409.  Alcohol  in  the  Liver.  — When  alcohol  is  drunk,  the 
portal  vein  carries   it   directly   to  the   liver.      There  the 
alcohol  greedily  uses  up  the  oxygen  needed  by  the  liver 
cells  for   their   vital    operations.     This    prevents    natural 
action  of  the  liver,  for  its  cells  have  not  enough  oxygen  to 
do  their  work  properly.     All  physicians  know  that  a  drunk- 
ard's liver  presents  a  greatly  modified  appearance.     The 
alcohol  does  not  build  up  useful  tissue,  but  if  taken  in 
weaker  form,  such  as  beer  and  wine,  it  promotes  an  abnor- 
mal deposit  of  fat  in  the  cells. 

410.  Drinking  whisky  and  other  distilled  liquors  causes 
the  connective  tissue  of  the  liver  first  to  increase  in  amount 
and  afterward  to  shrivel  and  harden,  drawing  up  into  many 
little  knots.     This  condition  is  called  " hobnailed"  or  "gin 
drinkers'  liver." 


THE  DIGESTION  231 

411.  Influence   of  Carriage  and  Dress  on  Digestion. — 

Faulty  carriage  of  the  body  and  relaxation  of  the  ab- 
dominal muscles,  which  lessens  the  abdominal  type  of 
respiration  and  diaphragmatic  motion,  are  among  the  most 
frequent  causes  of  sluggishness  in  hepatic  circulation  and 
secretion.  Disorders  of  the  stomach  and  intestines  are 
likely  to  produce  abnormal  conditions  of  the  liver.  Im- 
proper dress  aggravates  all  of  these  conditions. 

Free  and  properly  related  movements  on  the  part  of  the 
stomach,  liver,  and  intestines  are  necessary  for  the  correct 
performance  by  these  organs  of  their  natural  functions. 
A  certain  amount  of  tension  within  the  abdomen  is  neces- 
sary if  the  organs  of  that  region  are  to  be  held  in  their 
proper  places  and  relations.  When  the  body  is  held  erect 
and  the  chest  is  kept  raised  to  its  normal  position ;  when 
the  abdominal  muscles  are  strong  and  are  not  allowed  to 
relax  and  thus  favor  the  descent  of  the  organs,  this 
abdominal  tension  and  the  proper  relations  of  the  organs 
are  possible.  Mothers  should  dress  their  children  so  that 
the  chest  may  have  the  greatest  possible  freedom  of  mo- 
tion. All  garments  should  be  suspended  from  the  shoul- 
ders, thus  preventing  the  downward  displacement  of  the 
stomach,  intestines,  kidneys,  liver,  etc.  Physicians  who 
have  given  the  subject  careful  study  agree  that  more 
than  fifty  per  cent  of  the  women  of  civilized  nations  have 
developed  the  condition  known  as  enteroptosis,  which  means 
that  of  the  stomach,  the  intestines,  frequently  the  kid- 
neys, and  sometimes  the  liver,  are  dragged  downward  and 
remain  permanently  out  of  proper  position.  This  condi- 
tion is  largely  responsible  for  the  debility,  backache,  head- 
ache, biliousness,  and  early  loss  of  complexion  with  which 
so  many  women  of  civilized  countries  are  afflicted.  Even 
if  suffering  from  the  enteroptosis  caused  by  methods  of 
dress,  those  who  have  strong  constitutions  and  who  keep 
the  body  healthy  by  living  much  out  of  doors,  may  enjoy 


232 


ELEMENTS   OF  PHYSIOLOGY 


moderate  comfort.  The  greater  proportion  of  women, 
however,  lack  these  conditions  and  hence  suffer  to  a 
greater  or  less  extent  from  the  symptoms  mentioned. 

412.  The  mistake  in  regard  to  dress  begins  so  early  in 
life  that  the  wearer  almost  ceases  to  consider  the  dis- 
comfort arising  therefrom.  Many  women  say  that  their 


_^>*s> 


FIG.  183. 


The  breastbone  cannot  be  moved  down  by 
a  corset.  Use  its  lower  end  for  a  sta- 
tionary point,  in  comparing  Figs.  183 
and  184.  How  much  have  the  liver  and 
stomach  descended  ? 


FIG.  184. 

How  far  have  the  kidneys  been  moved  ? 
Has  only  the  middle  of  the  transverse 
colon  descended  or  all  of  it?  Is  the 
waist  of  Fig.  183  deformed  more  than 
the  usual  amount  ? 


dress  is  perfectly  comfortable,  because  they  do  not  know 
what  comfort  and  freedom  is.  Dr.  Kellogg  found  the  aver- 
age waist  measure  of  girls  from  9  to  1 2  years  of  age  to  be 
23 \  inches,  and  he  found  the  waist  measure  of  young  ladies 
from  1 8  to  30  years  of  age  to  be  23 \  inches.  If  their 
waists  had  been  allowed  to  grow  as  God  designed,  they 
would  have  become  28  or  30  inches  in  circumference.  In 
all  these  years  the  bones,  muscles,  digestive  and  other 


THE  DIGESTION  233 

organs  had  been  growing,  but  the  waist  had  not.  The 
organs  had  been  growing  out  of  place.  The  muscles  of 
the  trunk  had  not  been  growing,  because  their  exercise  was 
prevented  by  tight  skirt-bands  or  corsets.  The  weak 
abdominal  muscles  become  distended  by  the  weight  of 
the  organs,  and  the  abdomen  sags  downward  and  extends 
too  far  forward.  The  proper  support  being  removed,  the 
stomach,  liver,  kidneys,  and  other  organs  sag  downward 
and  drag  and  pull  upon  their  points  of  attachment  and 
cause  pain  and  distress  in  all  parts  of  the  trunk,  especially 
in  the  back,  because  of  the  pulling  and  stretching  of  the 
nerves  leading  from  these  organs  to  the  spine. 

413.  Having  worked  perseveringly  to  get  the  organs 
down  out  of  the  waist  and  make  it  small,  the  woman  would 
now  give  treasures  to  get  them  back  again.  The  contor- 
tions such  as  the  "  straight  front "  and  "  Grecian  bend  " 
are  attempts  to  conceal  deformities  of  waist  and  abdomen. 
The  cause  of  the  trouble  dates  back  to  the  year  the  grow- 
ing girl  began  to  wear  her  skirts  tied  around  the  waist  in- 
stead of  sewed  to  the  upper  part  of  the  dress.  Growth  at 
the  waist  immediately  ceased.  If  she  had  only  waited,  the 
chest  and  hips  would  have  developed  and  the  waist  would 
have  become  rightly  proportioned  soon  enough.  It  is  said 
that  a  majority  of  women  are  sufferers  from  headache, 
backache,  and  other  weakness  which  could  have  been  obvi- 
ated by  comfortable  and  therefore  graceful  clothing.  This 
want  of  foresight  has  made  invalids  and  nervous  wrecks  of 
thousands  of  women,  who  try  one  surgeon  and  physician 
after  another,  seeking  relief.  Such  a  woman  is  unsuited  for 
the  proud  position  of  presiding  over  the  household,  her 
diseases  cast  a  gloom  over  the  family  life.  The  world  is 
not  so  bright  to  her,  and  life  is  not  so  joyous  as  it  should 
be.  Yet  many  a  delicate  woman  would  have  been  able 
to  retain  her  health  if  she  had  not  had  a  dissipated  and 
drunken,  or  a  nervous,  tobacco-soaked,  husband.  It  is 


234 


ELEMENTS   OF  PHYSIOLOGY 


possible  also  that  many  a  man  would  have  been  able  to 
bear  up  through  the  struggles  of  life  and  finally  to  suc- 
ceed, instead  of  succumbing  to  stimulants  and  dissipation, 
if  he  had  not  been  burdened  with  a  hysterical  invalid  for 
a  wife,  instead  of  a  brave,  cheerful,  and  healthy  woman. 
The  drooping  lily  style  of  woman  has 
become  very  distasteful  to  men;  the 
drinking,  dissipating  man  is  becoming 
equally  repulsive  to  women.  Health 
is  an  indispensable  foundation  for 
happiness. 

THE  KIDNEYS 

414.  The  kidneys  lie  one  on  each 
side  of  the  vertebral  column,  against 
the  rear  wall  of   the  abdomen,  on  a 
level  with  the  lower  ribs.     They  are 
purplish  red  organs,  about  four  inches 
long  and  two  inches  broad,  and  some- 
what bean-shaped.      A  man's  kidney 
(Fig.   185)  is  very  much  like  a  pig's 

FIG.  185.—  Kidneys  and  kidney,  which  you  may  have  seen. 

Bladder.  J      .      .         J 

415.  A   large  artery,  the  renal  ar- 

K,    kidneys;      Ur,    ureters;  .         .          .  .  , 

/?/,  bladder:  i,  openings  of  tery,    leads    from    the    aorta   to    each 
tt  kidney,   and  a  large   vein,   the   renal 


aom;  v.c.i.,  inferior  vena  vem    leads  from  each  kidney  to  the 

cava  (see  Plate  V). 

inferior  vena  cava.  There  also  passes 
out  from  each  kidney  a  white  tube  called  a  ureter.  The 
two  ureters  run  down  the  back  and  open  into  the  bladder 
(Plate  V). 

416.  Function.  —  Urea  is  the  most  important  substance 
excreted  by  the  kidneys.  It  is  brought  by  the  blood  to  the 
kidneys,  and  you  learned  that  it  is  probably  formed  in  the 
liver.  It  is  a  nitrogenous  substance,  and  is  more  abundant 
if  a  large  amount  of  proteid  food  is  eaten. 


THE  DIGESTION 


235 


417.  In     summer,     when 
the   circulation  in  the  skin 
is   active,    the   secretion    of 
the    kidneys    diminishes    in 
amount.    On  the  other  hand, 
cold  drives  the  blood  from 
the  surface  to  the  internal 
organs,  and  the  secretion  of 
the    kidneys    is    increased, 
although  probably  but  little, 
if  any,  more  urea  passes  off. 

418.  The    blood    leaving 
the    active    kidney    is    still 
of  a  bright  red  color.     It  is 
probably    the    purest   blood 
in  the  body.     Can    you  ex- 
plain why  this  is  so. 


FIG.  186.-— Section  of  the  Kidney. 

Ct,  cortex;  AT,  medulla;  .Py,  pyramid; 
P,  pelvis;  U,  ureter;  RA,  renal 
artery. 


CHAPTER  XIV 
HYGIENE  OF    DIGESTION 

419.  Is  Good  Health  "  Catching  "  ?  —  A  wit  once  said  that 
if  he  had  been  consulted  at  the  creation  of  the  world,  he 
would  have  made  good  health  "  catching  "  instead  of  dis- 
ease. Observations  show  that  happiness,  industry,  health, 
faith,  and  other  of  the  strong  elements  that  make  up  life,  are 
more  contagious  than  misery,  idleness,  sickness,  worry, 
and  the  other  weak  elements  that  tend  to  destroy  life. 
Fear  causes  a  tightening  of  the  muscles  and  a  waste  of 
energy,  as  well  as  oppressed  breathing  and  a  lack  of  oxy- 
gen. Courage  brings  calm,  full  breathing  which  purifies 
the  blood,  and  a  steady  and  economical  use  of  the  muscles 
which  saves  the  vital  energy.  A  brave  and  cheerful 
visitor  can  inspire  an  ailing  friend  and  assist  in  his  re- 
covery. A  happy,  unselfish  teacher  or  pupil  can  dispel 
worry  or  gloom,  and  impart  strength  and  increased  power 
for  work  to  the  whole  school.  The  body  tends  to  health 
and  not  to  disease.  The  dyspeptics  that  we  see  have  been 
able  to  break  down  their  health  only  after  long-continued 
attacks  upon  it,  and  outrages  many  times  repeated.  Fresh 
air  brings  health,  and  forces  its  way  into  the  home  to 
bring  it,  but  the  dyspeptic  made  every  attempt  to  keep  it 
out.  Sunshine  brings  health,  but  he  shut  himself  up  in  a 
stuffy  ill-lighted  office,  a  slave  to  dollars  or  to  fame.  He 
curtained  the  sunshine  out  from  the  home  to  protect  the 
carpets  and  hangings  from  fading.  Exercise  brings  health, 
but  the  promptings  to  stir  about,  to  walk,  to  run,  or  to  work 

236 


HYGIENE   OF  DIGESTION 

with  the  hands,  were  repressed  until  the  impulses  ceased. 
When  activity  was  lessened,  the  appetite  for  food  dimin- 
ished, but  instead  of  following  the  prompting  of  nature,  he 
sprinkled  more  salt  and  pepper  and  other  condiments  upon 
the  food,  that  he  might  eat  with  an  unnatural  appetite. 

420.  By  keeping  up  these  artificial  ways  for  months  and 
years,  he  at  last  succeeded  in  breaking  down  his  health.     It 
took  more  perseverance  to  weaken  the  body  than  it  will 
take  to  make  it  strong  again.     There  must  be  a  return  to 
reasonable  ways  of  living  with  trust  in  the  inherent  ten- 
dency  of   the   cells  to  restore   soundness  when   given   a 
chance.     If,  however,  he  commits   the  folly  of    thinking 
that  months  are  not  needed  for  recovery,  but  that  disease 
brought  on  by  months  or  years  of  wrong  living  can  be 
cured  in  a  few  days  by  taking  magical  drugs  and  patent 
medicines,  he  will  probably  injure  himself  still  more  and 
lose  his  chance  of  recovering  sound  health. 

421.  Environment  of  Primitive  Man.  —  It  is  believed  that 
the  race  originally  did  not  dwell  in  houses,  and  had  few 
tools  or  cooking  utensils.     Man  probably  first  lived  in  the 
tropics  and  subsisted  upon  the  fruits  which  ripened  in  the 
never-ending  summer,  and,  as  he  migrated  to  the  colder 
climates,  subsisted  upon  the  results  of  the  chase.     That 
individual  who  refused  to  peel  his  apples  because,  as  he 
said,  Adam  had  no  pocket  knife,  and  slept  with  his  windows 
open  because  Adam  had  no  house,  had  a  right  principle  in 
view.     If  his  teeth  were  as  sound  as  the  teeth  of  primitive 
man,  and  his  habit  of  mastication  as  thorough,  the  peeling 
would  be  only  an  aid  to  digestion. 

422.  Man  possesses  a  stomach  intended  to  digest  the 
pure  food  of  the  forest,  obtained  by  activity  in  the  open 
air.     If  a  man  eats  plain  food  and  leads  an  active  life,  his 
appetite  is  a  perfect  guide.     If  he  does  not,  it  is  unsafe  to 
trust  to  the  appetite  alone,  for  the  reason  that  he   lives 
under  conditions  unlike  those  for  which  this  instinct  was 


238  ELEMENTS   OF  PHYSIOLOGY 

built  up.  A  cow's  appetite  is  a  certain  guide  to  her  among 
poisonous  plants  and  berries,  yet  she  will  eat  a  bucket  of 
paint  and  harm  herself ;  this  is  beyond  the  range  of  her 
inherited  habits.  Even  if  man's  instincts  had  their  early 
strength,  they  could  hardly  guide  him  among  the  many 
food  concoctions  and  preparations  undreamed  of  by  primi- 
tive man.  We  can  train  our  taste  into  wrong  ways,  and 
we  can  likewise  train  it  into  right  ways  and  into  liking 
food  that  we  know  is  wholesome. 

423.  The   uncertainties  of  man's  early  savage  life,  the 
times  of  drought  or  of  ill  luck  in  hunting,  accustomed  his 
cells  to  periods  of  starvation  and  repletion,  of  feast  and  of 
famine.      His    organs  could   withstand  irregularity  better 
than  they  could  withstand  continuous  scarcity  or  overfeed- 
ing, continuous   overwork  or  idleness.      The    Indian   lies 
around  the  camp  and  gorges  himself  in  times  of  peace  and 
plenty,  his  cells  laying  up  strength  which  enables  him  to 
follow  the  trail  or  the  chase  for   days  at   a   time,    going 
sometimes  fifty  miles  a  day.     It  is  said  that  the  business  of 
one  age  becomes  the  recreation  of  the  next. 

424.  It   is    found  that   returning  to   natural  habits  by 
going  on  camp  hunts  and  fishing  trips  is  one  of  the  most 
effective  hygienic  measures  for  the  restoration  of  health. 

425.  Hobbies  about  Nutrition.  — The  subject  of  food  and 
digestion  is  a  more  complicated  one  than  that  of  exercise 
or  breathing,  and  more  common  sense  is  required  to  master 
it.     Therefore,  more  persons  fail  to  master  it,  and  allow 
their  minds  to  come  to  rest  on  some  one  fact  or  view  of 
the  subject  and  so  become  extremists. 

426.  Hot  Water  Fad.  —  Some  would  cure  every  digestive 
ill  by  means  of  water.     Their  belief  is  "water  internally, 
externally  and  eternally."     They  sometimes  drink  it  as  hot 
as  it  can  be  borne,  yet  hot  water  is  very  relaxing  to  the 
walls   of  the  stomach  and  weakens  the  flow  of  the  gastric 
juice.     This    extreme    belief    arose    from    the    fact   that 


HYGIENE    OF  DIGESTION  239 

h.ot  water  removes  the  mucus  from  a  stomach  suffering 
from  catarrh  (or  congestion)  and  diminishes  the  activity  of 
the  gastric  glands  if  too  much  acid  is  being  secreted. 

427.  Raw  Food  Fad.  —  Some  persons  have  a  fad  called 
the  raw  food  doctrine,  and  eat  no    cooked  food.     They 
should    consider  that    man's  digestive  organs  are  not   as 
vigorous  now  as  they  were  ages  ago,  before  he  learned  the 
use  of  fire.      This  fad  is  a  reaction   from  bad  cooking. 
Cooked  vegetables  are  more  likely  to  ferment  in  a  weak 
stomach   than   raw   vegetables.      The  thorough  chewing 
required  by  raw  food  is  an  advantage  to  digestion. 

428.  No  Condiment  Fad.  —  Some  persons  will  not  have 
condiments  or  any  kind  of  seasoning,  not  even  salt,  in  their 
food.     This   is  because    many  cooks  destroy  the  natural 
flavors  of  the  food  by  bad  cookery  and  hide  the  result  by 
high  seasoning.      There  are  many  delicate  and  delicious 
flavors  of  grains,  fruits,  and  fresh  vegetables  that  a  natural 
appetite  takes  pleasure  in ;  but  because  of  long  use  of  badly 
cooked  and  highly  seasoned  foods  the  sense  of  taste  in 
many  persons  has  become  so  depraved  and  dull  that  they 
have  only  five  kinds  of  taste  left :  the  taste  for  grease,  salt, 
pepper,  vinegar,  and  sugar.      Their   dull  nerves    require 
everything  to  be  very  salty  or  peppery  or  sweet  or  greasy 
or  sour. 

429.  Other  Fads  which  may  be  mentioned  are  the  vege- 
tarian fad,  distilled  water   fad,  fasting  fad,   no  breakfast 
fad. 

430.  THOUGHT  LESSON.     Cooking.  Meat.  —  i.  In  mak- 
ing soup,  why  should  the  meat  be  put  in  while  the  water 
is  cold  ? 

2.  In  roasting  meat,   why  should  the  oven  be  hot  at 
first,  and   more    moderate    afterward  ?     How    should  you 
regulate  the  temperature  in  boiling  or  stewing  meat  ? 

3.  What  happens  to  salt  or  anything  salty  on  a  cloudy, 
damp  day  ?     This  is  because  the  salt  attracts .     This 


240 


ELEMENTS   OF  PHYSIOLOGY 


shows  that  meat  should  not  be  salted  until  after  it  has 
been  cooked,  because  if  salted  before,  the  salt  will . 

4.  Very  -  —  meat   should  never  be   broiled,  because 
broiling  does  not  it.      Such   meat  should  be  — 

b ed  or  st ed. 

5.  Meat  is  allowed  to  become  grease-soaked  when  it  is 

by  -    -  cooks.     The  two  ways  to  prevent  this  are  to 

have  the  grease  very ,  use  very ,  simply  greasing 


FIG.  187.  —  Teeth  of  Cat. 


FIG.  188.  — Teeth  of  Man. 


FIG.  189.  — Teeth  of  Cow. 


FIG.  190.  —  Teeth  of  Hog. 


6.  Bread.  —  Bread  crust  causes  the to  be  used  more 

and  cleans  them.  It  will  not together  in  the  stomach 

like  the  crumb.  It  increases  the  quantity  of  the ,  and 

is  more  digestible  than  the  crumb,  since  the has  been 

changed  by  slow  heat  to .  Therefore  loaves  or  bis- 
cuit should  be  [large  or  small  ?]  and  they  should  [touch 
or  be  separated  ?]  in  the  pan. 

How  can  you  tell  whether  the  oven  has  been  too  hot 
while  the  bread  was  cooking  ? 


HYGIENE   OF  DIGESTION  241 

431.  Classification  of  mammals  according  to  food  :  — • 


CARNIVORA,  OR 
FLESH-EATERS. 

HERBIVORA,  OR 
HERB-EATERS. 

OMNIVORA,  OR 

ALL-EATERS. 

FRUGIVORA,  OR 
FRUIT-EATERS. 

Examples. 

Cat,  dog,  lion, 
tiger,  bats. 

Cow,       sheep, 
horse,  camel. 

Hog,  peccary. 

Man,           ape, 
monkey. 

Length  of 
Alimen- 
tary canal.1 

3  times  length 
of  body. 

30  times  length 
of  body. 
Stomach  with 
five        cham- 
bers. 

10  times  length 
of  body. 

12  times  length 
of  trunk  or 
body. 

Teeth. 

Pointed        for 
tearing   flesh. 
Canine   teeth 
long. 

Made  of  alter- 
nate layers  of 
enamel      and 
dentine,  form- 
ing ridges  for 
grinding. 
Canines  lack- 
ing. 

Cutting     teeth 
project         in 
front. 
Canines  form 
tusks. 

Teeth  of  even 
length,    close 
together.    No 
space  between 
teeth. 
Canines      not 
projecting. 

Extremi- 
ties. 

Sharp  claws. 

Hoofs. 

Hoofs. 

Flattened  nails. 

Colon. 

Smooth. 

Sacculated. 

Smooth. 

Sacculated. 

432.  THOUGHT    LESSON.      Comparison  of    Mammals.  — 

Which  of  the  kinds  would  probably  have  quickest  digestion  ? 
Slowest  ?  Which  eats  food  that  would  spoil  if  not  quickly 
digested?  Which  eats  food  that  would  keep  sound?  Is 
there  an  appropriate  relation  between  extremities  and  teeth? 
Which  kind  of  mammals  has  closest  resemblance  to  the 
frugivora?  Which  kind  has  least  resemblance  to  the 
f rugivora  ?  Why  ? 

433.  Man's  Original  Food  Resources  and  how  they  have 
been  enlarged.  —  Cuvier,  Owen,  Huxley,  and  other  com- 
parative anatomists  agree  that  man  was  originally  frugiv- 

1  Body  measured  from  tip  of  nose  to  end  of  backbone.  Mammals  are  the 
highest  vertebrates.  The  mother  nourishes  the  young  with  milk.  The 
mammary  glands  are  on  the  abdomen  for  all  of  the  kinds  of  mammals  except 
the  fourth.  With  the  frugivora  they  are  on  the  thorax. 


242  ELEMENTS  OF  PHYSIOLOGY 

orous :  he  ate  tree  fruit,  both  nuts  and  fleshy  fruits.  Tree 
fruits  contain  all  the  four  chemical  classes  of  foods,  —  pro- 
teids,  fats,  carbohydrates,  and  minerals.  The  present 
sources  of  his  food,  besides  the  original  nuts  and  fruits, 
are  flesh,  grains,  herbs,  and  he  has  added  them  to  his 
dietary  probably  in  the  order  named  above.  In  the  warm 
regions  of  the  earth,  the  banana,  plantain,  mango,  orange, 
and  cocoanut  trees  bear  their  luscious  fruit  the  year 
round.  But  the  multiplication  of  the  race  and  perhaps 
times  of  drought  and  famine  led  man  to  use  the  food 
stored  up  in  the  flesh  of  other  animals  which  had  obtained 
it  from  grass  and  herbs.  This  necessity  doubly  increased 
with  migration  to  colder  climates.  In  the  frigid  zones 
the  inhabitants  live  very  largely  on  animal  food.  They 
consume  immense  quantities  of  blubber,  or  the  fat  of 
certain  animals,  such  as  the  whale,  the  walrus,  and  the 
seal.  This  kind  of  diet,  by  sustaining  the  necessary  bodily 
heat,  enables  these  people  to  withstand  the  intense  cold  to 
which  they  are  subjected. 

Grains  in  their  natural  state  are  too  small  and  collect- 
ing them  was  too  tedious  before  the  time  of  that  long-for- 
gotten genius  who  first  thought  of  cultivating  them  in 
order  to  improve  them.  Hunting  is  known  to  have  pre- 
ceded agriculture  in  all  wild  tribes.  After  flesh  and 
grains,  last  of  all  came  vegetables.  Fruits  and  grains 
belong  to  the  seed  part  of  the  plant.  The  coarser  woody 
leaves  and  stem  and  roots  were  probably  not  added  to 
man's  food  until  the  art  of  cooking  was  much  advanced. 
The  degree  of  digestibility  seems  to  coincide  in  most 
persons  with  the  order  of  adoption  of  the  classes  of  foods 
by  the  race.  If  one  leads  a  sedentary  life,  or  his  digestion 
becomes  impaired,  the  weedy,  fibrous  vegetables  should  be 
the  first  to  be  discarded  from  the  diet,  while  flesh  and 
fruits  seem  to  furnish  the  main  substance  for  invalids  even 
after  grains  and  starches  prove  hard  to  digest. 


HYGIENE    OF  DIGESTION  243 

434.    Composition  of  Foods. 


PRO- 

TEIDS. 

FATS. 

CARBOHY- 
DRATES. 

WATER. 

SALTS. 

CELLU- 
LOSE. 

I.  NUTS. 

Pecan 

10  3 

70.8 

Id.  3 

Walnut     .... 

15.8 

57-4 

16! 

• 
13- 

Almonds  .... 

23-5 

53- 

12. 

7.8 

Cocoanut  .... 

5.6 

51- 

35- 

4- 

II.   FRUITS. 

Sugar. 

Peach  

0.5 

1.6 

g- 

Plum    

0.5 

2.O 

78. 

Blackberry     .     .     . 

0.5 

4.0 

/**• 

86. 

Cherry      .... 

0.5 

10. 

84. 

12.  C 

.1  C 

Fi  en- 

4O 

1  .4 

J 

Banana     .... 

•w 

5-0 

20. 

75- 

III.   ANIMAL  FOOD. 

Lean  beef     .     .     . 

20.5 

3-5 

•9 

75- 

1.6 

Fat  pork  .... 

9.8 

48.9 

39-° 

2-3 

Smoked  ham 

24.8 

36.5 

27.8 

10.  1 

Whitefish      .     .     . 

18.1 

2.9 

78.0 

I.O 

Poultry     .... 

21.0 

3-8 

74.0 

1.2 

Oysters     .... 
Cow's  milk    . 

3-5 

0.5 
4.0 

4.0 

80.0 
87.0 

0.7 

6.0 

12.  C 

12.  0 

f.~    C 

I  .O 

3-2 

Cheese      .... 

33-5 

24-3 

36'.8 

5-4 

4.29 

Butter       .... 

o-3 

91.0 

6.0 

2.1 

IV.   PODS  OR  LEGUMES. 

Starch. 

3-5 

24.5 

2.O 

C2 

12.  C 

2.8 

Peas    . 

21   7 

I  .Q 

C7~7 

I  2. 

Peanuts    .... 

*»  •/ 

29.47 

49-20 

1  6.2 

2.77 

V.   GRAINS. 

Wheat  flour  (white) 

I  I.O 

2.0 

70.3 

15.0 

1.7 

0.3 

Wheat  bread      .     . 

8.0 

r.e 

49.0 

40.0 

1.2 

o-3 

Oatmeal    .... 

12.6 

5.6 

63.0 

15.0 

3-° 

1.6 

Maize  (corn)      .     . 

TO.O 

6.7 

64.5 

13-5 

1.4 

1.5 

Rice     

c.o 

0.8 

83.2 

IO.O 

o.  *> 

A  r\ 

VI.  VEGETABLES. 

j 

Potatoes  .... 

2.0 

0.16 

21.0 

74.0 

I.O 

I.O 

Cabbage  .... 

1.8 

5.0 

5.8 

91.0 

0.7 

1.5 

244  ELEMENTS  OF  PHYSIOLOGY 

435.  Nuts  are  the  most  concentrated  and  nutritious  of  all 
foods.     Beefsteak  is  three  fourths  water,  while  nuts  are 
less  than  one  fourth  water  (see  Table).    Nuts  are  how  many 
times  as  nutritious  as  beefsteak  ?     This  refers  to  the  nut 
"  meats  "  or  kernels.     Nuts  may  be  said  to  consist  of  one 
half  fat,  one  fourth  proteid,  and  the  remaining  one  fourth 
water  and  mineral.     The  fat,  unlike  that  of  butter,  oil,  and 
fat  meat,  is  emulsified  in  nuts,  and  does  not  need  to  be 
divided  up  before  absorption  by  the  lacteals  in  the  small 
intestine.     Their  density  encourages  the  habit  of  thorough 
chewing.     Nuts  are  made  up  of  little  cells,  each  of  which 
has  its  proportion  of  proteids,  fat,  and  dextrine,  a  kind  of 
sugar.     The  small  boy  climbs  the   tree  and  gathers  the 
nuts,  cracks  and  eats  them,  and  digests  them  thoroughly. 
The  man  stays  in  his  office,  has  some  one  else  to  gather 
them,  masticates  less  thoroughly,  and  he  may  find  them 
less  digestible,  especially  if  he  always  eats  a  full  meal  before 
taking  the  nuts.     Green  or  rancid  nuts  are  not  digestible. 
Nuts  should  be  eaten  during  the  meal  the  same  as  meat. 
They  are  digestible  raw.      Persons  who  usually  eat  nuts 
after   they  have  already  eaten  too  much,  consider  them 
very  indigestible.     They  are  not  good  for  the  digestion  if 
eaten  between  meals,  or  if  not  thoroughly  chewed. 

436.  Pods,  or  Legumes,  resemble  nuts  very  closely  in 
chemical  composition,  but  they  require  long  and  thorough 
cooking.     Their  seed  coats,  or  hulls,  consist  of  cellulose  or 
woody  fiber,  which  may  well  be  removed.     The  hulls  can 
be  loosened  by  soaking  them  in  cold  water  before  they  are 
cooked.     Beans  and  peas  have  been  called  the  lean  meat 
of  the  vegetable  kingdom,  and  they  take  the  place  of  meat 
with  those  who  discard  meat  (vegetarians). 

437-  Fruits  have  four  important  advantages  :  (i)  Their 
agreeable  flavors  are  a  natural  and  healthy  stimulus  to  the 
digestion.  (2)  They  contain  vegetable  acids  (either  citric, 
malic,  or  tartaric)  that  are  perfect  germicides,  and  are 


HYGIENE    OF  DIGESTION  245 

very  powerful  in  purifying  the  alimentary  canal.  (Fruits 
have  almost  no  proteid.  How  does  this  show  that  a  fruit 
diet  would  starve  the  germs,  even  if  the  fruit  acids  did  not 
destroy  them  ?)  (3)  They  contain  very  valuable  mineral 
salts  that  are  of  highest  use  to  the  blood  and  tissues. 
(4)  The  carbohydrate  in  ripe  fruits  is  all  in  the  form  of 
levulose  or  fruit  sugar,  which  is  predigested  starch,  and  is 
absorbed  without  digestion.  With  these  advantages,  there 
is  the  disadvantage  that  fruits  are  largely  water,  so  that 
the  nutriment  they  contain  is  very  scant,  except  in  the  case 
of  grapes,  bananas,  and  olives. 

438.  The  proverb  that  fruit  is  golden  at  breakfast,  silver 
at  noon,  and  lead  at  night,  is  not  true.     Fruit  is  golden  at 
all  times,  if  it  is  sound  and  ripe,  and  if  the  stomach  is  not 
already  filled  with  food.     Fruit  juices  are  valuable  as  restor- 
atives .to  health,  since  they  tax  the  digestive  organs  very 
little  and  are  quickly  assimilated.     Since  germs  will  not 
grow  in  fruit  juices,  a  fruit  diet  for  several  meals  will  dis- 
infect the  alimentary  canal  and  ward  off  a  "bilious"  attack. 
Juicy  apples,  pears,  lemonade,  orangeade,  pomegraniteade, 
ripe  peaches,  etc.,  are  pleasanter  than  medicines. 

439.  Animal  Food.    Meat.  —  Proteid  is  the  principal  food 
substance  in  meat.     Beef  contains  the  largest  amount  of 
any  of  the  common  meats,  and  pork  the  least.     The  fat  of 
meat  is  also  of  great  importance  :  fat  is  abundant  in  pork. 
Meat  that  is  salted  and  smoked,  or  dried,  or  prepared  in 
any  way  so  that  germs  will  not  grow  in  it,  can  be  kept  for 
a  long  time,  but  its  digestibility  is  greatly  impaired.     This 
is  because  its  fibers  have  been  hardened  so  that  the  gastric 
juice  cannot  readily  penetrate  them.     Meat  which  has  much 
connective  tissue  is  tough ;  the  most  tender  and  digestible 
of  meats  consist  almost  wholly  of  muscular  tissue  and  fat. 

440-  Experiments  show  that  ordinarily  one  fifth  of  the 
proteid  in  vegetable  food  passes  through  the  intestine  un- 
digested and  unabsorbed,  and  is  thus  wasted,  while  only 


246  ELEMENTS   OF  PHYSIOLOGY 

one  thirtieth  of  the  proteid  in  meat  escapes  digestion.  A 
pound  of  fat  requires  three  times  as  much  oxygen  in  its 
oxidation  as  a  pound  of  sugar,  and  therefore  yields  three 
times  the  heat  and  energy.  The  digestibility  of  fat  is  in- 
creased by  the  fact  that  it  ferments  with  difficulty,  while 
sugar  and  starch  ferment  more  easily.  Meat  should  be 
thoroughly  cooked  to  avoid  the  danger  of  diseases  from 
the  trichina  and  other  parasites. 

441.  Milk  of  cows  is  suited  for  calves,  and  was  intended 
to  be  obtained  by  sucking  and  to  be  swallowed  gradually. 
It  contains  too  large  a  proportion  of  proteid  for  infants, 
and  therefore  water  is  added.     The  casein  or  proteid  part 
is  coagulated  in  flakes  by  the  rennin,  and  when  a  child 
throws  up  coagulated  milk,  it  does  not  mean  that  it  is  suf- 
fering from  indigestion,  although  it  may  sometimes  mean 
that  it  is  being  overfed.     The  tendency  of  milk  to  pro- 
duce "  biliousness  "  and  constipation  in  some  persons  may 
be  explained  as  follows :   when  adults  drink  sweet  milk 
rapidly,  especially  toward  the  end  of  the  meal,  when  much 
acid  is  present  in  the  stomach,  the  acid   coagulates  the 
casein  into  large  lumps  of  curd,  which  may  seriously  dis- 
turb digestion,  for  milk  was  not  intended  to  be  drunk  rap- 
idly.    Heat  retards  the  production  of  acid  in  the  gastric 
juice  and  increases   the   secretion  of   rennin.      If  taken 
before  meals,  hot  and  slowly,  milk  will  agree  with  those 
who  have  found  it  to  produce  indigestion.     Buttermilk  is 
one  of  the  most  digestible  of  foods. 

442.  Cheese  is  a  concentrated  food,  and  is  one  of  the 
cheapest  although  not  one  of  the  most  digestible  forms  of 
proteid. 

Does  a  pound  of  eggs  contain  more  or  less  nourishment 
than  a  pound  of  meat  (§  434)  ?  At  usual  prices,  which 
is  more  economical,  eggs  or  meat  (see  Table,  §  434)  ? 

443.  Meat  Extracts.  —  Researches  concerning  the  nutri- 
tive value  of  meat  extracts,  show  that  in  none  of  them  is  a 


HYGIENE    OF  DIGESTION  247 

large  quantity  of  food  concentrated  in  a  small  bulk  as  the 
public  are  led  to  believe.  A  glass  of  milk  contains  far 
more  nourishment  than  a  cup  of  beef  tea.  The  best  way 
to  get  the  nourishment  out  of  a  steak  is  to  eat  it.  The  beef 
extract  contains  but  a  fraction  of  the  proteids  in  beef,  and 
all  of  the  nitrogenous  waste  material  allied  to  urea.  The 
most  nutritious  part  of  the  beef  is  not  soluble,  but  the  ex- 
cretory part  of  the  meat  is  soluble,  and  this  is  found  in  the 
beef  tea  or  beef  extract.  This  extract  throws  work  upon 
the  kidneys  and  is  harmful.  The  part  of  the  beef  that 
has  most  value  is  thrown  away  in  making  the  extract. 
Many  lives  are  no  doubt  annually  sacrificed  by  starvation 
through  the  popular  faith  in  beef  tea  as  a  concentrated  and 
nourishing  food.  Beef  tea  and  meat  juice  can  be  used  as 
flavoring  agents  with  other  food  since  they  stimulate  the 
secretion  of  pepsin,  but  they  should  not  be  regarded  as 
real  food. 

444.  By  drying  meat  it  can  be  reduced  to  one  fourth  its 
weight  (since  it  is  three  fourths  water).     Thus  100  pounds 
of  beef  can  be  reduced  to  25  pounds  and  sold  in  a  form 
useful  to  travelers.     The  meat  will  keep  fresh  as  long  as  it 
is  kept  dry.    Water  is  added  to  the  meat  when  it  is  cooked. 

445.  Grains.  —  Nearly  all  the  starch  of  our  food  is  sup- 
plied by  grains.     They  also  contain  from  8  to  1 5  per  cent  of 
a  proteid  called  gluten.     The  chief  grains  are  wheat,  oats, 
barley,  corn,  rice,  buckwheat.     The  more  of  gluten  there  is 
in  grain,  the  more  gluey  or  sticky  its  flour  will  be.     Sticky 
flour  will  retain  the  bubbles  of  gas  formed  from  baking-pow- 
ders or  by  the  growth  of  the  yeast  plant.     Wheat  has  much 
gluten,  and  its  flour  makes  very  light  bread.     Coarse  meal 
has  not  enough  gluten  to  make  it  very  sticky,  and  corn 
bread  will  not  rise  well.     Corn  contains  more  fat  than  any 
other  grain,  yellow  corn  containing  more  fat  than  white 
corn.     Rice  is  poorer  in  albumin  and  richer  in  starch  than 
any  other  grain  (see  Table,  §  434). 


248  ELEMENTS   OF  PHYSIOLOGY 

446.  Three  Kinds  of  Flour.  —  There  are  three  ways  of 
grinding  flour:  (i)  Using  the  whole  grain  and  the  husk 
which   incloses   the   grain.      This    makes    graham    flour. 
(2)  By  using  the  whole  of  the  grain.     This  makes  whole 
wheat  flour.     (3)  By  rejecting  the  outer  and  darker  portion 
of  the  grain,  thus  losing  part  of  the  gluten  and  retaining  all 
of  the  starch.     This  makes  the  ordinary  flour.     Graham 
flour  is  most  stimulating  to  peristalsis  in  the  canal.     Its 
large  amount  of  waste  matter  furnishes  something  for  the 
intestine  to  contract  upon,  and  thus  sweep  all  waste  matter 
on  and  out  of  the  body,   contributing  to  the  cleanliness 
of  the  canal.     It  sometimes  causes  congestion  in  irritable 
stomachs.     Sometimes  flour  which  is  merely  dark  with  dirt 
is  sold  for  graham  flour.      The  whole  wheat  flour  is  stimu- 
lating to  the  canal  but  is  not  irritating.     Some  believe  that 
it  furnishes  more  of  the  mineral  salts  and  bone-making  and 
tissue-building  material  than  the  fine  flour. 

447.  The  Cooking  of  Grains. — You  learned  that  the  starch 
of  fruit,  when  it  ripened,  .was  turned  to  sugar.     Ordinary 
cooking  bursts  the  cells  of  starch  in  the  grain  and  begins 
the  transformation  into  dextrin,  a  substance  intermediate 
between  starch  and  sugar.     This  is  a  great  help,  for  the 
saliva  does  not  act  upon  raw  starch,  and  the  pancreatic 
juice  acts  only  slightly  and  after  several  hours'  delay.    Cook- 
ing that  amounts  to  little  more  than  moistening  and  heating 
the  starch,  is  a  disadvantage,  and  makes  it  more  likely 
to  ferment  than  if  eaten  raw ;  but  thorough  cooking  adds 
greatly  to  the  digestibility  of  starch.     Oatmeal,  cracked 
wheat,  and  other  grain  foods  should  be  cooked  at  least  40 
minutes. 

448.  How  Grains  may  be  made  to  resemble  Fruit.  —  If 
cooked  several  hours,  the  starch  of  grains  is  so  thoroughly 
dextrinized  that   it  is  changed  to  sugar  almost  instantly 
when  brought  in  contact  with  the  saliva.     Grains  may  be 
cooked  during  the  preceding  meal  and  the  cooking  finished 


HYGIENE   OF  DIGESTION  249 

in  preparing  the  meal  at  which  they  are  to  be  eaten. 
If  oatmeal  and  other  mushes  are  sticky,  it  shows  the 
presence  of  half-cooked  starch.  The  yellow  crust  of 
bread  will  not  stick  together  because  the  starch  has  been 
changed  into  the  last  stage  of  dextrin,  called  yellow  dex- 
trin. Rice  and  oatmeal  may  be  first  browned  in  the 
oven  and  afterward  steamed.  Toast  and  brown  crust 
are  almost  as  digestible  as  ripe  fruit  and  are  given  to 
invalids. 

449.  Cellulose  has  the   same   chemical   composition  as 
starch.     It  forms  the  cell  walls  and  woody  fibers  of  plants, 
and  is  hardly  digested  at  all  by  man ;  hence,  starch  requires 
cooking  to  burst  the   cellulose   envelopes   of   the   starch 
grains.     Cellulose  and  water  are  the  chief  constituents  of 
grass,  and  of  greens,  cabbage,  and  other  fibrous  vegetables. 
It  forms  the  fibers  in  watermelons,  which  also  contain  cane 
sugar,  the  sweetest  of  the  sugars.   The  woody  skins  of  beans 
and  peas  are  cellulose.     Hence,  many  find  the  legumes 
more  digestible  in  a  puree,  or  cooked  with  the  skins  re- 
moved.    Cellulose   is   the  natural  stimulant  to  peristalsis 
and  activity  of  the  canal.    Cattle  digest  cellulose,  and  with 
them  it  takes  the  place  of  starch. 

450.  Vegetables.  —  Root  vegetables  and  tubers,  such  as 
potatoes,  sweet  potatoes,  and  turnips,  contain  a  small  per- 
centage of  starch.    But  vegetables  in  general  consist  almost 
entirely  of   water   and  woody  fiber   (cellulose).     This   is 
especially  true  of  green  vegetables,  or  those  which  consist 
of  the  leafy  part  of  the  plant.     But  green  vegetables  con- 
tain nucleo-albumin,  or  iron-bearing  albumin,  which  is  of 
great  value  to  the  blood  and  tissues.     This  form  of  albu- 
min is  easily  destroyed  in  the  intestine  before  it  reaches 
the  blood,  if  fermentation  takes    place.     As   some   leafy 
vegetables  are  more  likely  to  ferment  if  cooked,  there  is  an 
advantage  in  eating  them  raw.     Iron  and  valuable  mineral 
salts  are  thus  obtained. 


250  ELEMENTS  OF  PHYSIOLOGY 

451.  The   nostrum  venders  who   shamelessly  advertise 
their  iron  tonics  "to  enrich  the  blood"  are  only  attempt- 
ing to  prey  upon  the  ignorant.     The  magical  power  of  the 
sun's  rays  can  turn  iron  into  food.     The  brown  color  of 
the  grain,  the  red  cheek  of   the  tomato,  strawberry,  and 
peach  are  due  to  iron,  and  iron  in  this  form  will  enrich 
the  blood.     For  a  student  to  learn  that  iron  colors  the  red 
corpuscles,  may  be  of  some  value,  but  if  the  only  purpose 
the  knowledge  serves  is  to  aid  in  entrapping  him  into  be- 
lieving that  the   patent-medicine  man  makes  a  valuable 
blood  tonic  out  of  rusty  nails  and  alcohol,  his  method  of 
study  has  not  cultivated  his  judgment,  nor  cured  him  of 
the  natural  propensity  to  jump  at  conclusions. 

452.  Leonard  Hill,  Professor  of  Physiology  in  the  Royal 
College  of  Surgeons,  says :   "  In  these  days  of  advertise- 
ments it  is  necessary  to  strongly  warn  the  reader  against 
the  lies  of  the  trader   and   the   quack.     The   method   of 
fortune-making  by  advertisement  is  to  sell  a  well-known 
and  cheap  article  at  a  dear  price,  under  a  new  name,  with 
a  flavor  added,  and  the  vaunted  pills,  when  submitted  to 
analysis  in  chemical  laboratories,  are  found  to  consist  of 
aloes,  salts,  or  other  common  drugs,  which  the  quack  buys 
for  a  few  pence  a  pound,  and  sells  for  a  shilling  an  ounce. 
Most  of  the   minor  ailments  are  produced  by  errors  in 
diet  and  lack  of   healthy  exercise.      These  ailments  are 
relieved  temporarily  by  a  purge,  and  the  public  are  per- 
suaded thus  to  buy  fruit  salt  or  pills  for  a  shilling,  when 
the  required  article,  aloes  or  Epsom  salts,  can  be  obtained 
for  a  penny.     Among  the   numberless   quack  medicines 
sold  for  nervous  exhaustion,  many  are  altogether  value- 
less, and  sometimes  contain   stimulants,  such   as    alcohol 
or  coca.     Nervous  exhaustion  can  be  cured,  not  by  drugs, 
but  by  changing  the  habits  of  life.     Bicycling,  bathing, 
and  gymnastic  exercises  are  worth  infinitely  more  than  all 
the  drugs  in  the  world.     Errors  in  living  can  be  atoned  for, 


HYGIENE    OF  DIGESTION 

not  by  the  taking  of  medicines,  but  by  learning  the  art  of 
living,  and  of  this  lesson,  spare  diet,  hard  work,  and  exer- 
cise form  the  first  and  last  page. 

"  In  countries  other  than  England  the  patent-medicine 
venders  are  forced  to  publish  the  ingredients  of  their  con- 
coctions, and  the  governments  warn  the  public  and  state 
the  nature  and  exact  price  of  the  ingredients.  In  England 
the  people  are  allowed  to  be  fooled  and  defrauded  of  mil- 
lions of  money  by  quacks,  while  the  government,  to  its 
disgrace,  does  nothing  to  protect  the  poor,  weak,  and 
the  ignorant  from  them." 

453.  Is  England  the  only  country  in  which  this  fraud- 
ulent business   is   allowed  to   flourish   unchecked  ?     The 
formula   should   be   required   by  law   to  be  printed  upon 
the  bottle.     Most  patent  medicines  in  large  bottles,  such 
as  sarsaparillas,  bitters,  etc.,  contain  about  the  same  pro- 
portion of  alcohol  as  brandy  contains.     Even  in  grogshops 
the  character  of  the  drink  that  is  being  sold  is  not  entirely 
misrepresented  to  the  customer. 

454.  An  Error  of  Vegetarians.  —  Those  with  whom  meat 
does   not  agree,  or   who   for  humane  scruples,  or  other 
causes,  adopt  a  vegetarian  diet,  sometimes  fall  into  serious 
error.     If  fruits  and  nuts  are  not  freely  used,  but  the  diet 
is  confined  to  grains  and  green  vegetables,  a  large  excess 
of  starch  is  consumed,  and  the  diet  is  very  bulky,  in  spite 
of  the  fact  that  it  is  greatly  lacking  in  fat  and  proteid. 
Persons  who  do  not  eat  meat  should  replace  the  proteid  of 
meat  with  that  of  nuts,  cheese,  beans,  and  peas,  and  employ 
fat  in  the  form  of  nuts,  cream,  milk,  eggs,  and  butter. 

455.  Many  millions  of  people,  the  most  populous  nations 
of  the  earth,  eat  no  meat.    The  inhabitants  of  the  countries 
largely  vegetarian  in  diet,  as  India,  China,  etc.,  constitute 
a  majority  of  the  human  race.     It  may  be  possible  that 
they  would  be  a  more  vigorous  people  if  they  lived  upon 
a  more  varied  diet.     People  of  warm  countries  flourish  on 


252  ELEMENTS   OF  PHYSIOLOGY 

a  vegetarian  diet ;  it  is  also  possible  to  do  so  in  a  temperate 
climate,  but  it  is  hardly  possible  in  the  frigid  zone.  An 
Eskimo  will  eat  fifteen  pounds  of  walrus  fat  in  a  day. 
Too  much  meat  in  the  diet  affects  students  and  sedentary 
individuals  more  injuriously  than  it  does  muscle  workers. 

456.  Should  the  Diet  be  Bulky  or  Concentrated  ?  —  The 
way   this   question   is  answered   will   determine   whether 
graham  or  white  flour  is  better,  whether  the  skins  of  beans 
and  peas  and  fruits  should  be  removed,  whether  one  should 
eat  coarse  vegetables,  such  as  cabbage,  greens,  celery.     It 
is  probable  that  the  true  answer  is  that  sedentary  persons 
with  weak  peristalsis  of  the  stomach  should  not  eat  much 
woody  material  as  it  causes  the  food  to  remain  too  long  in 
the  stomach  before  it  is  reduced  to  chyme,  while  persons 
whose  business  requires  muscular  activity  and  whose  ali- 
mentary canal  possesses  a  more  vigorous  peristalsis,  will 
find  a  bulky  food  preferable. 

457.  If,  some  hours  after  eating  boiled  cabbage,   you 
could  still  taste  it,  or  another  could  detect  the  odor  of  it  on 
your  breath,  what  inference  might  be  drawn?     If  greens 
were  added  to  the  usual  dinner,  and  you  had  a  feeling  of 
heaviness  or  dullness  after  dinner,  what  would  you  infer? 
What  would  be  the  conclusion  if  you  felt  more  vigorous 
than  usual?     If   you   had   fallen   into  the   bad   habit   of 
taking  the  feverish  haste  of  business  to  the  dinner  table 
with  you,  but  on  one  day  you  "  took  things  easy  "  at  dinner, 
as  well-bred  people  should,  eating  very  leisurely,  and  you 
had  a  feeling   of   unusual   lightness   and  energy  in   the 
evening,  what  would  you  infer? 

458.  Should  a  Person  drink  at  Meals?  —  Slow,  careful 
eaters,  whose  throats  refuse  to  receive  anything  that  is  not 
thoroughly  chewed  and  mixed  with  saliva,  should  not  drink 
while  eating,  as  it  would  dilute  the  digestive  fluids  already 
abundant.     But   those   who  eat  rapidly  or  do  not  chew 
thoroughly,   often    find    that    some    liquid    at    meals   aids 


HYGIENE    OF  DIGESTION  253 

digestion,  for  with  this  manner  of  eating,  the  natural 
secretions  are  insufficient.  Should  the  liquid  be  sipped 
with  each  mouthful,  or  should  it.be  taken  at  intervals  and 
when  the  mouth  is  empty  ?  Which  method  would  have 
less  effect  in  decreasing  the  flow  of  saliva  ?  Which  method 
would  be  more  likely  to  increase  the  tendency  to  bolt  the 
food  down  ? 

459.  Individual  Wants.  —  The  student  readily  sees  that 
the  question  of  individual  needs  is  of  importance.     There 
is  truth  in  the  old  adage,  "  What  is  one  man's  meat  is  -an- 
other man's  poison."     No  cast-iron  rules  can  be  laid  down 
for  any  one's  life.     Common  sense  can  never  be  dispensed 
with.     Persons  with  moderate  powers  of  observation  find 
by  experience  what  is  best,  and  they  should   have  will 
power  enough  to  adhere  to  what  they  find  is  best  for 
them,  although  opposite  ideas  may  be  presented  to  them 
as   the  only  correct   way,  by  persons  of   narrow  views. 
What  is  enough  for  one  is  a  surplus  for  another.     Sex, 
age,  occupation,  and  heredity,  each    has  its  influence  on 
diet.     The  wear  and  tear  of  an  active  body  requires  a  class 
of  food  which  to  one  of  sedentary  occupation  would  be 
a  burden.      Exercise   lights   the   fire   that   burns  up  the 
refuse  of  the  body,  and  thus  it  increases  the  appetite  and 
strengthens  the  digestion. 

460.  Indigestion  in  Sound  Digestive  Organs.  —  If  a  person 
confines  himself  closely  with  brain  work  and  takes  no  exer- 
cise whatever,  he  may  not  digest  his  food  well,  but  he  need 
not  think  his  digestive  organs  unsound,  and  begin  dieting 
himself.      He    should  take  more  exercise,  and  by  better 
habits  of  life  stir  up  his  circulation,  use  the  food  stored  in 
the  cells,  and  they  will  become  hungry  for  more,  and  diges- 
tion will  be  perfect.      There  is  a  saying,     "  You  can  lead  a 
horse  to  water,  but  you  can't  make  him  drink."     So  you 
may  put  food  in  the  alimentary  canal,  but  you  cannot  make 
the  cells  assimilate  it?  although,  by  the  use  of  much  pepper 


254  ELEMENTS  OF  PHYSIOLOGY 

and  condiments,  you  may  have  aroused  an  appetite  for  it. 
Such  food  may  not  be  digested,  but  it  does  not  mean  that 
the  digestion  is  weak,  it  means  only  that  too  much  food 
and  too  many  condiments  have  been  used. 

461.  Two   Ways  out  of  a  Difficulty.  —  Exercise  is  the 
best  way  out  of  digestive  troubles  ;  yet,  if  a  student  or  office 
man  is  under  the  delusion  that  he  "just  simply  has  not 
time  "  to  take  plenty  of  exercise,  he  may  partly  meet  the 
difficulty  and  keep  his  brain  clear  by  an  abstemious  diet. 
Many  a  plow  boy  has  gone  to  college,  and  failing  to  take  up 
athletics  or  to  perform  any  manual  labor,  yet  has  continued 
to  eat  the  same  quantity  of  food  which  before  sustained 
him  in  his  labor,  but  which  now  only  clogs  the  organs  and 
stupefies  the  brain.      Thus  his  work  as  a  student  does  not 
accomplish  half  that  it  should  accomplish. 

462.  Cooking.  —  Meat  should  be  roasted  by  putting  it  into 
a  hot  oven  at  first,  to  form  a  crust  to  keep  in  the  juices,  then 
lowering  the  temperature  of  the  oven  to  prevent  drying  out 
and  hardening.     When  broiling  meat,  it  should  be  turned 
over  every  ten  seconds  to  send  the  juices  back  and  prevent 
their  escape,  thus  broiling  the  meat  in  the  heat  of  its  own 
juices.     Tender  meat  should  be  broiled,  but  tough  meat  is 
often  better  fried.     Grease  for  frying  should  be  boiling  hot 
when  the  meat  is  put  in,  to  form  a  crust  and  prevent  any  of 
the  grease  from  soaking  in.  Fried  meat  that  is  grease-soaked 
is  the  most  unhealthful  of  all  cooked  meat.     Meat  should 
not  be  salted  until  after  it  has  been  cooked,  for  salt  draws 
the  juices  out. 

463.  Bread  is  best  if  made  of  whole-wheat  flour.      It 
should  be  cooked  in  a  slow  oven,  so  that  the  inside  of  the 
loaf  may  be  well  baked.     The  loaves  should  be  made  small 
and  not  touching,  so  that  there  may  be  much  crust.     Crust 
(i)  cleans  the  teeth  like  a  brush  and  makes  them  healthy 
from  use ;  (2)  it  increases  flow  of  saliva  by  its  dryness  and 
the  longer  chewing  required ;  (3)  it  is  more  easily  digested 


HYGIENE   OF  DIGESTION  2$$ 

than  the  crumb,  or  white  portion,  as  it  resembles  sugar.  Bea- 
ten breadis  the  most  digestible,  like  the  hoe  cake  and  johnny- 
cake  and  other  unleavened  breads.  Yeast  bread  comes  next 
in  digestibility.  Baking  powders,  if  they  contain  alum, 
and  soda,  if  not  thoroughly  neutralized  by  sour  buttermilk, 
are  injurious  even  to  the  healthy.  It  is  quite  possible 
that  the  depression  and  nervousness  caused  by  innutrition 
from  trying  to  live  on  such  abominations  as  soda  biscuit  and 
grease-soaked  food,  are  often  the  forerunners  of  drunken- 
ness and  other  misfortunes  that  a  small  amount  of  intelli- 
gence in  the  kitchen  would  have  prevented. 

464.  Yeast  belongs  to  the  class  of  plants  called  fungi, 
which  can  live  in  darkness,  and  have  neither  leaves  nor  blos- 
som. Most  plants  get  nourishment  from  the  soil,  air,  and 
water,  but  yeast  and  other  fungi  derive  their  sustenance 
from  vegetable  or  animal  matter  in  process  of  decomposi- 
tion. Yeast  plants  are  microscopic  cells  of  oval  shape,  and, 
like  other  plants,  require  food  in  liquid  form.  They  can- 
not absorb  dry  or  solid  food.  Their  most  suitable  food  is 
sugar.  The  flour  of  wheat  contains  starch,  a  small  amount 
of  which  is  converted  into  sugar  by  the  diastase  which  lies 
next  the  bran.  Yeast  grows  best  at  a  temperature  of  from 
70°  to  80°.  A  slow  growth  at  a  lower  temperature  favors 
the  development  of  other  micro-organisms,  which  make  the 
yeast  unhealthy  and  produce  bad  flavors.  With  a  high  tem- 
perature its  growth  is  rapid  and  of  extremely  short  duration. 
Fermentation  may  go  through  several  stages ;  in  the  first 
stage,  or  alcoholic  fermentation,  the  yeast  decomposes  the 
sugar,  splitting  it  into  alcohol  and  carbon  dioxid  gas. 
This  is  the  stage  for  bread-making,  the  gas  causing  the 
bread  to  rise.  In  the  second  stage,  or  vinegar  fermentation, 
alcohol  is  changed  to  acetic  acid  —  the  acid  in  vinegar. 
Hard  wheat  has  more  gluten  than  other  wheat,  and  the 
bubbles  formed  in  its  flour  will  not  break  easily.  Why 
does  bread  from  such  wheat  rise  well  ?  Why  is  bread  set 


256  ELEMENTS   OF  PHYSIOLOGY 

in  a  warm  place  to  rise  ?  Why  does  it  "fall"  if  left  to  stand 
too  long?  Under  what  conditions  does  bread  made  from 
yeast  become  sour  ?  Why  does  bread  set  to  rise  in  a  cold 
place  sometimes  have  a  bad  flavor  ? 

465.  Irish  potatoes,  to  become  mealy  instead  of    soggy, 
should  be  put  into  boiling  water,  and,  after  they  are  cooked, 
the  water  should  be  poured  off,  and  the  pot  should  be  set 
on  the  back  of  the  stove  for  the  potatoes  to  dry.     Roasting 
them  in  the  oven  with  their  skins  on  also  retains  their  flavor 
and  makes  them  mealy. 

466.  Cucumbers  are  as  digestible  as  apples  if  eaten  raw 
and  when  sweet.      Pickles  are'  absolutely  indigestible,  and 
are  treated  as  foreign  substances.     Onions    are  better   if 
cooked,  to  drive  off  the  acrid,  irritating  oil.     Raw  cabbage, 
which  is  water  and  woody  fiber,  is  treated  by  the  stomach 
as  a  foreign  substance,  and  sent  promptly  to  the  intestine; 
but  the  stomach  attempts  to  digest  boiled  cabbage,  and  it 
remains  there  several  hours.     The  skins  of  peanuts,  after 
boiling  water  has  been  poured  over  them  for  a  moment,  can 
be  easily  removed.     If  then  allowed  to  simmer  on  the  stove 
for  hours,  until  they  can  be  easily  pressed  through  a  col- 
lander,  they  form  a  nutritious  and  palatable  food,  with  the 
addition  of  a  little  salt.     Raw  and  roasted  peanuts  are  not 
easy  to  digest.     Eggs  should  be  cooked  by  placing  them  in 
boiling  water  and  taking  the  pot  off  the  stove.     They  cook 
while  the  water  is  cooling,  and  the  albumen  is  jellied  but  not 
hardened. 

467.  Is  Alcohol  a  Food?  —  When  alcohol  is  taken,  about 
ninety-five  per  cent  of  it  is  oxidized  and  changed  into  car- 
bon dioxid  and  water.     This  was  found  out  many  years 
ago  and  raised  the  question  as  to  whether  it  should  be 
classed  as  a  food.     Investigations  were  made,  and  the  re- 
sult was  that  alcohol  was  classed  with  the  poisons  and  not 
as  a  food.     The  question  has  been  reopened  several  times 
in  the  last  half-century,  but  always  with  the  same  result. 


HYGIENE   OF  DIGESTION 

Scientific  men  generally  continue  to  classify  it  as  a  poison 
and  not  as  a  food.  Morphine,  mushroom  poison,  strych- 
nine, and  other  dangerous  poisons  are  oxidized  in  the 
body  and  yield  up  their  energy,  yet  they  are  recognized 
as  poisons.  A  substance  cannot  be  classified  as  a  food 
simply  because  it  is  oxidized  in  the  body. 

468.  Leading  scientists  define  a  food  as  follows  :  A  food 
is  a  substance  of  such  a  nature  that,  when  absorbed  into  the 
blood,  it  nourishes  the  body  without  injuring  it. 

469.  Sugar  is  a  food  but  a  solution  of  sugar  can  undergo 
a  change  caused  by  the  growth  of  millions  of  yeast  plants 
and  the  food  is  lost.     The  change  is  called  fermentation, 
and  alcohol  is  one  of  the  poisonous  products  of  this  process 
of  decay  or  fermentation. 

The  condition  of  the  body  after  it  has  oxidized  alcohol 
is  quite  different  from  its  condition  after  it  has  oxidized 
sugar  or  bread.  Benzine  is  very  easily  oxidized.  If 
poured  upon  the  fire  of  a  locomotive,  it  would  make  the 
water  boil  so  rapidly  that  there  would  be  danger  of  strain- 
ing or  bursting  the  boiler.  It  would  burn  so  rapidly  as 
almost  to  make  an  explosion,  and  a  very  large  part  of  the 
heat  caused  by  the  oxidation  would  be  lost.  A  stove 
needs  a  slower  burning  substance  than  gunpowder  or  ben- 
zine. A  locomotive  needs  a  slow-burning  fuel  which 
will  develop  heat  at  such  a  rate  that  it  will  be  possible  to 
utilize  it.  The  body  needs  even  slower  burning  substances 
than  the  locomotive,  such  as  sugar,  starch,  and  fat ;  not  a 
more  rapidly  burning  substance,  such  as  alcohol,  which  in 
burning  will  weaken  the  tissues  and  shock  and  injure  the 
delicate  cells  of  the  one  who  drinks  it.  In  the  chapter  on 
the  blood  it  was  learned  that  alcohol  does  not  even  cause  a 
gain  of  heat  in  the  end,  since  the  paralysis  of  the  capillaries 
resulting  from  a  drink,  causes  the  warmth  to  be  taken  to 
the  surface  and  escape,  so  that  the  body  is  cooler  than 
before  the  drink. 


258  ELEMENTS   OF  PHYSIOLOGY 

470.  True  food  does  not  burn  in  the  blood ;  it  is  stored 
in   the  cells  in    the  form   of   very   unstable   compounds. 
These  compounds  break  down  under  the  stimulus  of  oxy- 
gen and  the  nerve  current,  and  set  free  energy.     The  cells 
of  the  nerves  and  muscles  correspond  to  the  furnace  and 
steam  chest  of  the  engine.     Suppose,  instead  of  pouring 
benzine  into  the  furnace,  you  burned  it  in  .the  cab  or  the 
smokestack.      Do  you  think  it  would  increase  the  power 
of  the  locomotive  ?     Alcohol  is  not  stored  in  the  cells,  nor 
does  it  enter  into  combination  to  form  the  energy  com- 
pound, the  breaking  down  of  which  sets  free  the  energy 
stored    up.      Alcohol   burns    quickly   after  entering   the 
body ;   a  large  part  of  it,  indeed,  never  gets  beyond  the 
liver,  and  is  burnt  in  this  long  suffering  organ.     But  some 
of  it  gets  into  the  general  circulation,  and  is  distributed 
throughout  the  body,  irritating  the  nerve  cells  and  poison- 
ing them  and  every  other  tissue. 

471.  Does  Alcohol  warm  the  Body  as  well  as  a  Coat  ?  — 
It  may  occur  to  a  user  of  alcohol  to  say,  "It  certainly 
gives  warmth,  for  it  burns ;  so  it  is  of  some  benefit.     It  is 
equal  to  a  good  overcoat,  if  it  is  not  food,  and  like  the 
overcoat,  it  may  save  the  burning  of  some  of  the  fuel-food, 
sugar  and  fat."     Benzine  may  tear  up  the  machinery,  but 
it  certainly  gives  heat.     But  suppose  you  put  most  of  the 
benzine  in  the  cab  just  before  the  furnace  door.     It  will 
use  up  the  oxygen  and  furnish  carbon  dioxid  in  the  draught 
to  the  furnace,  instead  of  fresh  air.     Will  this  make  the 
fire  burn  brighter,  or  will  it  smother  it  ?     This  is  exactly 
what  alcohol  does ;  it  uses  up  the  oxygen  supplied  to  the 
blood  by  the  ever-faithful  lungs,   and  the  blood  carries 
carbon  dioxid  to  the  brain,   muscles,    and   other  tissues. 
An  overcoat  does  not  smother  the  tissues  by  using  up  the 
oxygen  they  need.     Thus  it  happens  that  the  drinker's 
nerves   become    deadened,  his  faculties   dulled,  his   mus- 
cles weak  and  unsteady.     If  he  drinks  much  at  a  time,  he 


HYGIENE    OF  DIGESTION 

falls  into  a  profound  stupor  —  he  is  "  dead  drunk."  Thus 
the  heat  from  the  oxidation  of  the  alcohol  prevents  the 
true  tissue  activity  which  is  necessary  for  the  life  pro- 
cesses, and  burdens  the  liver  with  an  unnecessary  activity 
in  destroying  the  poisons.  The  poison,  in  the  meanwhile, 
has  paralyzed  the  arterial  walls  and  allowed  the  capillaries 
to  become  flushed,  and  the  warmth  of  the  blood  rapidly 
escapes  through  the  skin.  By  using  up  the  oxygen, 
it  checks  the  production  of  heat  in  the  usual  way,  while 
the  heat  resulting  from  its  own  oxidation  is  soon  lost  to 
the  body,  and  much  more  of  the  bodily  heat  besides. 

472.  One  ounce  of  alcohol  requires  two  ounces  of  oxy- 
gen to  oxidize  it.     The  lungs  furnish  twenty-four  ounces 
of  oxygen  daily.     How  many  hours  will  it  take  the  lungs 
to  supply  oxygen  enough  to  oxidize  one  ounce  of  alcohol  ? 
Three  drinks  of  whisky  contain    one   ounce  of  alcohol. 
How  many  drinks  would  be  necessary  to  use  up  a  day's 
supply    of   oxygen  ?     A   man    would   probably   die   long 
before  he  had  drunk  that  quantity. 

473.  The  Secret  of  the  Influence  of  Alcohol.  —  It  is  a  fact 
that  we  are  clearly  conscious  only  of  the  energy  that  we 
are  exerting,  and  not  of  the  energy  that  is  stored  up  in  our 
bodies.     When  alcohol  is  first  taken,  the  cells  treat  it  as  an 
intruder,  and  the  activity  excited  by  the  attempt  to  expel  it 
from  the  body  causes  the  man  to  think  the  alcohol  is  giv- 
ing him  strength,  when  it  is  only  taking  it  away.     It  de- 
ludes the  drinker  into  thinking  that  he  is  strong,  though 
before  the  drink  he  had  been  feeling  weak ;  warm,  though 
he  had  been  feeling  cold ;  it  makes  him  careless,  when  he 
had  been  careworn ;  confident,  when  he  had  been  feeling 
timid.     These  are  pleasant  effects.     But  the  later  effects 
of  headache  and  depression  and  gloom,  worse  than  before, 
he  does  not  attribute  to  alcohol,  since   they   are    not  so 
closely  associated  in  time  with  the  drinking.    He  does  not 
remember  the  crazy  or  idiotic  scenes  that  were  enacted  when 


260  ELEMENTS   OF  PHYSIOLOGY 

he  was  wholly  under  its  influence,  the  wild  or  maudlin  talk, 
the  loss  of  all  self-control,  the  quarrel  with  the  best  friend, 
and  the  abuse  of  wife  and  children,  and  afterward  the 
drunken  stupor.  If  he  did  recognize  these  effects,  he  would 
stop  the  use  of  the  poison.  If  remembered  at  all,  they  are 
only  as  an  unreal  dream  that  is  not  a  part  of  his  life.  A 
man  once  fell  into  a  fire  while  intoxicated,  and  just  as  fall- 
ing into  cold  water  will  sometimes  sober  a  man,  the  pain 
and  danger  brought  him  to  his  senses ;  he  realized  what 
alcohol  was  doing  for  him  and  never  drank  again.  The 
various  inebriate  cures,  so  called,  are  founded  on  the  prin- 
ciple of  making  the  patient  disgusted  with  alcohol  by 
secretly  adding  some  nauseating  drug  to  the  drink,  thus 
giving  the  man  the  belief  that  alcohol  is  making  him  sick. 
As  long  as  the  belief  in  the  repulsiveness  of  its  effects  re- 
mains, the  man  can  abstain ;  but  most  drunkards  relapse 
into  their  old  ways.  Their  bodies  have  been  already 
ruined,  and  they  have  no  strength  of  will  left.  When 
they  once  drink  again,  the  association  of  alcohol  with 
the  agreeable  emotions  previously  mentioned  is  renewed 
and  the  power  of  the  habit  reasserts  itself. 

474.  Time  for  Eating.  —  Different  nations  have  various 
habits  of  eating.     The  number  of  meals  varies  from  two 
to  five,  or  even  eight,  meals  daily.     Such  facts  show  the 
adaptability  of  the  stomach  to  different  habits.     It  is  an 
organ  which  readily  forms  habits,  and  is  greatly  benefited 
by  regularity.     If  a  person  avoids  disturbing  the  stomach 
between  meals  and  allows   it   needed  rest,  both  appetite 
and  digestion   are    promoted.     Three  meals  a  day  seem 
to  be  needed,  especially  by  hard  workers.     The  Greeks 
ate  two  meals  a  day,  and  developed  the  most  beautiful  and 
perfect  bodies  in  the  world,  as  shown  by  the  statues  left 
by  them. 

475.  Very  active  exercise  tends  to  hinder  the  work  of  the 
stomach,  but  facilitates  that  of  the  intestines.     For  a  half- 


HYGIENE   OF  DIGESTION  26l 

hour  after  a  full  meal,  hard  work  of  every  kind  should  be 
avoided,  but  hard  work  an  hour  or  two  later  will  aid  diges- 
tion. The  arrangement  of  the  meals  must  take  into  ac- 
count the  other  habits  of  the  individual.  For  example,  if 
three  meals  are  eaten  in  twenty-four  hours,  the  last  ought 
to  be  the  lightest ;  but,  as  business  is  transacted  in  large 
cities,  a  business  man  can  hardly  find  time  for  a  hearty 
meal  in  the  middle  of  the  day.  Hence  he  does  right  in 
eating  a  lunch  at  noon,  and  having  the  heartiest  meal  come 
in  the  evening,  when  the  day's  labor  is  over  and  there  is 
time  to  relax.  If  he  takes  the  principal  meal  in  the  latter 
part  of  the  day,  he  should  not  eat  very  heartily  the  next 
morning  or  during  business  hours ;  to  do  so  would 
surfeit  the  system.  Late  suppers  should  not  be  eaten,  as 
they  prevent  sound  sleep.  The  lower  animals  may  lie 
down  in  the  shade  and  sleep  after  eating,  but  it  is  only  for 
a  short  nap.  A  nap  of  ten  minutes,  just  long  enough  to 
bring  about  relaxation,  is  often  of  benefit  after  a  meal. 
During  sleep  the  heart  beats  less  frequently  and  with  less 
force ;  the  lungs  breathe  less  freely ;  the  brain  ceases  its 
activities ;  the  muscles  relax  and  become  motionless ;  peri- 
stalsis and  secretion  in  the  alimentary  canal  become  slow, 
and  the  digestive  organs  should  have  rest  If  a  person  is 
troubled  with  a  too  great  flow  of  blood  to  the  brain,  some 
light,  digestible  article  of  food  taken  just  before  retiring 
may  bring  sleep ;  but  it  should  be  taken  simply  to  regu- 
late the  circulation,  and  should  be  so  digestible  as  to  give 
little  work  to  the  stomach.  A  farmer  will  do  a  better  after- 
noon's work  if  he  will  rest  for  half  an  hour  after  the  noon 
meal. 

476.  The  rule  that  every  individual  must  be  a  law  unto 
himself  may  be  abused  by  those  who  consult  their  appe- 
tites alone  without  reference  to  their  common  sense.  If 
we  believe  that  regularity  in  eating  is  desirable,  the  stom- 
ach and  appetite  can  be  trained  to  it,  although  if  one  is 


262  ELEMENTS   OF  PHYSIOLOGY 

used  to  eating  at  all  times  and  between  meals,  the  desire 
to  do  so  may  remain  for  a  time.  An  appetite  for  whisky 
is  an  acquired  one,  and  it  is  not  an  evidence  of  a  normal 
and  healthy  demand.  Emaciated  and  half-starved  persons 
may  suffer  from  want  of  appetite,  but  it  may  be  a  sign  that 
they  should  increase  the  activity  of  other  organs,  as  the 
muscles,  not  that  they  should  eat  insufficient  food. 

477.  A  good  and  healthy  appetite  comes  from  the  ex- 
penditure of  energy  and  rebuilding  of  the  tissues,  and  a 
person  with  such  an  appetite  enjoys  best  the  simple  foods 
that  will  best  give  energy  and   build   tissue.     The  best 
pleasures  of  eating  are  for  those  who  have  appetites  of 
this  kind,  not  for  the  epicure  or  glutton.     This  is  only  one 
example  of  the  general  truth  that  mere  pleasure  seekers 
do  not  have  the  best  pleasures ;  but  they  enjoy  life  best 
whose  living  is  complete,  all  the  duties  and  pleasures  of 
life  being  given  their  place,  and  none  allowed  to  usurp. 

478.  Subject  for  Debate.  —Resolved,  That  the  evils  result- 
ing from  bad  food  and  improper  eating  in  the  dining  room 
(aside  from  the  inestimable  benefits  of  food)  have  been  as 
great  a  curse  to  the  human  race  as  the  evils  resulting  from 
the  barroom. 

479.  THOUGHT    LESSON.     Clothing.     The  Head.  —  The 
position  and  extent  of  bald  spots  show  that  baldness  is 

caused  by .     The  best  kind  of  a  hat  is  [stiff  or  soft  ? 

light  or  heavy  ?  ventilated  by  holes  or  air-tight  ?]  and  worn 
[as  much  or  as  little  ?]  as  possible. 

The  Neck.  —  The  neck  is  very  [flexible  or  inflexible  ?] 
It  is  healthier  [with  or  without  ?]  covering.  Stiff  or  high 
neck  clothing  [destroys  or  preserves  ?]  its  beautiful  curves, 
and  makes  the  neck  [skinny  or  full  ?]  and  makes  one 
[more  or  less  ?]  apt  to  take  cold. 

The  Trunk.  —  The  most  flexible  portion  of  the  trunk  is 

the .  I  find  by  measuring  with  a  tape  line  that  the 

circumference  of  my  chest  is inches  more  with  the 


HYGIENE   OF  DIGESTION  263 

lungs  expanded  than  when  they  are  contracted.  This  is 
called  chest  expansion. 

My  waist  expansion  is  inches.  If  I  have  my 

clothing  cut  to  fit  the  larger  waist  measure,  and  support  it 

by  the  waist,  its  weight  will  cause  it  to when  the  waist 

contracts  in  breathing.  If  cut  to  fit  the  smaller  waist 

measure,  the cannot  and  my  breathing  will  be 

.  The  [shoulder  or  waist  ?]  is  made  mostly  of  tough 

bone  and  muscle,  it  contains  no  delicate  vital  organs,  it  does 

not  expand  or  contract ;  it  is  horizontal  while  the is 

vertical.  Therefore  the is  better  for  a  support  to  the 

clothing  than  the  .  The  seven  vital  organs  at  the 

waist  are  the  st ,  1 ,  sp ,  two  k ,  p ,  and 

a  portion  of  the  large . 

The  weight  of  the  clothing  on  the  shoulders  may  flatten 
the  chest  and  draw  the  shoulders  forward  if  the  weight  is 
supported  over  the  front  of  the  chest.  Therefore  the  weight 
should  fall  mostly  at  the  sides.  (The  buttons  for  men's 
suspenders  should  be  at  the  sides,  just  over  the  pockets.) 

The  "  Health  "  corsets,  and  "  Good  Sense  "  health  waists, 
with  straps  at  shoulders,  are  misnamed,  for  as  worn  the 
straps  are  loose  and  useless.  No  clothing  can  be  supported 
from  the  shoulders  unless  it  is  loose  enough  to  slip  down  at 
the  waist  when  unfastened  or  loosened  at  the  shoulders. 

Among  the  first  five  of  acquaintances  thirty  years  old 

or  older,  of  whom  I  happen  to  think, are  sickly.  Of 

five  gentlemen, are  sickly. 


APPLIED  PHYSIOLOGY 
EXERCISE  I 

1 .  How  do  you  explain  the  difference  in  the  way  a  dog  eats  meat 
and  a  horse  eats  grain  ?    (Compare  with  Question  8.) 

2.  Clothing  and  shelter  for  man  or  beast  economize  what  kind  of 
food? 


264  ELEMENTS   OF  PHYSIOLOGY 

3.  Why  does  wheat  bread  rise  better  than  corn  bread  ? 

4.  Why  is  corn  bread  one  of  the  most  fattening  of  grain  foods  ? 

5.  Why  is  it  that  you  can  tell  best  about  the  digestibility  of  bread 
while  you  are  slicing  it  ? 

6.  What  kind  of  persons  would  not  find  it  well  to  take  a  long  walk 
before  breakfast  ? 

7.  Why  are  late  suppers  unhealthful  (§  475)? 

8.  Why  should  bread  remain  longer  in  the  mouth  than  meat? 

9.  In  snowballing  what  is  the  appearance  of  the  hands  when  they 
itch  from  cold  ?     Why  is  it  that  ice  water  does  not  satisfy  the  thirst, 
but  often  produces  a  craving  to  drink  more  water  ? 

10.  Why  is  it  more  difficult  to  swallow  a  small  pill  than  a  large  one 
(§373)?    " 

EXERCISE  II 

11.  When  is  hunger  a  safe  guide  ? 

12.  Why  does  not  fat  meat  taste  as  well  in  summer  as  in  winter  ? 

13.  Name  organs  which  receive  more  benefit  from  the  blood  than 
they  give  to  it. 

14.  Name  organs  which  give  greater  benefits  to  the  blood  than  they 
receive  from  it. 

15.  Why  should  pork  be  thoroughly  cooked  ? 

1 6.  What  necessary  step  in  preparing  salt  meat  to  be  cooked  lessens 
its  nutrutive  value  ? 

17.  Should  biscuits,  having  a  yellow  tint  or  dark  spots  due  to  soda, 
be  eaten  or  thrown  away  ? 

1 8.  Why,  during  an  epidemic,  are  those  who  have  used  alcohol  as  a 
beverage,  usually  the  first  to  be  attacked  ? 

19.  What  is  the  effect  of  alcohol  upon  albuminous  substances  ? 

20.  Explain  how  it  is  that  when  people  speak  of  an  inactive  liver 
they  usually  mean  an  overworked  one  (§§  407, 408). 

EXERCISE  III 

21.  How  does  the  possession  of  a  gall  bladder  furnish  evidence  that 
man  should  have  meal  times  and  not  eat  at  all  times  ? 

22.  Who  attains  greater  success  in  life  and  true  happiness,  the  man 
who  makes  millions  of  dollars  but  loses  his  health  by  close  application 
to  money  making,  and  has  to  live  on  gruels  and  soups,  and  does  not 
have  sound  sleep,  or  the    man  who    makes  a  living  and  no  more, 
sleeps  soundly,  enjoys  his  food,  and  has  strong  nerves  ?     Which  do 


HYGIENE    OF  DIGESTION  26$ 

you  regard  as  a  truly  successful  man  ?     Which  does  public  opinion  re- 
gard as  more  successful  ? 

23.  Do  you  buy  more  wood  (cellulose)  when  you  buy  beans  or  when 
you  buy  nuts  (§  434)  ? 

24.  Do  you  buy  more  water  when  you  buy  bread  or  when  you  buy 
meat  ? 

25.  Which  is  true,  the  original  saying:  "  Stuff  a  cold,  and  you  will 
have  to  starve  a  fever,"  or  the  modern  way  of  stating  it  ? 

26.  Why  is   soda  sometimes  good  medicine  to  neutralize  a  sour 
stomach,  and  very  bad  for  digestion  if  eaten  in  bread  (§§  91,  377)? 

27.  What  advantage  in  digestibility  may  a  hot  biscuit  have  over  a 
loaf  of  stale  bread  ?     Vice  versa  ? 

28.  Some  physiologists  hold  that  the  eating  of  much  meat  causes  an 
irritable   temper.     Does  your    observation  of  others  or  your  personal 
experience  confirm  or  disprove  this  ? 

29.  Why  do  people  who  live  in  overheated  rooms  often  have  poor 
appetites  ? 

30.  Why  may  the  taking  of  prepared  pepsin  weaken  the  stomach  ? 

31.  Why  is  there  often  an  outbreak  of  colds  when  a  warm  moist  spell 
of  weather  succeeds  several  weeks  of  cold  dry  weather  (§§  6,  587)  ? 

32.  Explain  how  the  stomach  may  be  weakened  by  the  eating  of 
"predigested  foods. 

NOTES 

1.  What  the  Carpenter  said.  —  "You  literary  fellows  talk  about  the 
breakfast  question.      All  you  need  to  do  is  to  get  out  and  do  some 
work.    Use  your  hands.     Take  some  exercise  like  I  do,  and  you  can 
eat  anything.     You  sit  there  all  day  cooped  up  in  your  office  and  write, 
write,  write.     You  cannot  enjoy  food  or  sleep  as  long  as  you  do  that. 
Come  out  here  and  shove  the  jack-plane  an  hour  or  two ;  that  will  give 
you  an  appetite.     Let  me  get  you  at  one  end  of  this  cross-cut  saw  at  six 
o'clock  in  the  morning,  and  I  will  settle  the  breakfast  question  for  you 
in  a  hurry.      You  will  have  no  need  of  patent  cereals  or  fancy  foods  in 
pasteboard  boxes." 

2.  Cotton  Seed  as  a  Food.  —  The  American  Analyst  says :   "  Two 
thirds  of  the  olive  oil  sold  in  the  markets  of  the  world  is  born  in  the 
cotton  fields  of  the  Southern  States." 

Dr.  Allan  McLane  Hamilton  says :  "  I  consider  one  of  the  most 
healthful  articles  of  diet  that  we  can  possibly  have,  to  be  cotton-seed  oil. 
It  is  one  of  the  best  fats,  and  is  much  more  healthful  than  lard." 

Dr.  R.  O.  Beard,  a  professor  in  the  College  of  Medicine,  Minneapolis, 


266  ELEMENTS   OF  PHYSIOLOGY 

Minn.,  says :  "  Cotton-seed  oil  is  a  wholesome,  nutritious  vegetable  oil 
which  delicate  stomachs  bear  without  injury." 

3.  The  Mouth  shirks  Duty  at  the  Expense  of  the  Stomach.  —  The 
average  chronic  dyspeptic  needs  to  eat  pure  food  and  avoid  soft  and 
sloppy  food.     Why  ?     Because  when  the  food  is  in  the  form  of  slops  it 
is  well  lubricated,  and  when  taken  into  the  mouth  it  goes  down  before 
you  can  say  "Jack  Robinson,"  and  the  food  has  not  had  saliva  mixed  with 
it  and  thus  escapes  mouth  digestion.     Now  mouth  digestion  is  just  as 
necessary  as  stomach  and  intestinal  digestion ;  the  mouth  must  do  its 
work  properly  in  order  that  the  other  steps  in  the  digestive  process  may 
be  well  performed.     The  process  of  digestion  is  like  setting  up  a  long 
row  of  bricks,  each  being  a  little  space  from  the  other,  so  that  when  the 
first  brick  is  tipped  it  strikes  the  next  brick  and  knocks  it  down,  and 
that  strikes  the  next,  and  so  on  till  all  the  bricks  are  down.    Mouth 
digestion  prepares  for  stomach  digestion.  —  Good  Health. 

4.  Sick  Headache,  and  How  to  Avoid  It.  —  Sick  headache  means 
germs  and  foul  matter  in  the  alimentary  canal,  especially  the  stomach. 
These  attacks  are  always  preceded  by  well-marked  symptoms ;  by  noting 
and  profiting  by  these,  and  by  using  common-sense  treatment,  no  one 
need  agonize  through  such  painful  experiences  at  any  time. 

Among  the  warning  symptoms  are  dullness,  sleepiness  after  eating, 
floating  specks  before  the  eyes,  a  coated  tongue,  and  often  constipation. 
Sometimes  there  is  a  voracious  appetite.  In  fact,  large  quantities  of 
food  are  taken  into  the  body  and  retained  there,  and  but  little  is  elimi- 
nated. The  natural  result  is  that  there  is  stagnation  from  clogging  up 
with  spoiled  food  and  retained  waste  matter.  The  poisons  produced  are 
carried  by  the  circulation  to  all  parts  of  the  body.  Much  blood  natu- 
rally goes  to  the  head,  and  with  it  a  large  amount  of  poison. 

Common  sense  would  say  that  when  the  source  of  a  disorder  is  known 
the  proper  thing  would  be  to  remove  it ;  instead  of  giving  some  opiate 
to  quiet  the  symptoms,  which  are  only  the  wise  protest  of  the  bodily 
organs  against  abuse,  it  would  be  more  rational  to  relieve  them  by 
removing  the  unhealthy  matter  from  the  stomach  and  bowels  ;  or  if  the 
treatment  is  begun  in  time,  all  that  may  be  needed  is  a  fast,  or  a  fruit 
diet  for  twenty-four  hours,  and  free  water  drinking,  to  give  the  sys- 
tem time  to  dispose  of  the  excess  of  waste  matter. 

—  J.  H.  KELLOGG,  M.D. 

5.  Pawlow,  an  eminent  Russian  medical  authority,  made  a  kind  of 
window  in  a  dog's  stomach,  so  that  he  could  look  in  and  see  what  was 
going  on.     He  found  that  when  he  brought  savory  food  to  the  dog  and 
placed  it  before  his  nose  and  eyes  and  didn't  let  him  eat  it  or  taste  of  it, 
by  looking  into  his  stomach  he  could  see  the  gastric  juice  trickling  down 


HYGIENE    OF  DIGESTION  267 

the  walls  of  the  stomach ;  he  could  see  that  the  stomach  was  getting 
ready  to  digest  that  food.  The  flavor  of  the  food  had  given  notice  that 
it  was  coming,  but  it  didn't  come,  so  the  poor  stomach  was  disap- 
pointed. In  like  manner  your  mouth  will  water  for  grapes  which  you 
see  and  which  are  out  of  your  reach,  and  so  a  boy's  mouth  will  water 
for  a  pie  which  is  placed  upon  a  top  shelf  or  somewhere  where  he  can 
see  it,  and  it  is  out  of  his  reach.  Now  when  this  dog  didn't  see  the 
food  brought  to  him  and  didn't  smell  of  it,  nor  get  a  chance  to  chew  it, 
and  it  was  surreptitiously  slipped  into  his  stomach,  there  was  no  flow 
of  gastric  juice,  and  no  digestion.  Now  if  you  eat  food  .too  fast,  or  in 
the  form  of  mushes,  for  example,  it  slips  down  into  the  stomach  before 
the  stomach  has  notice  of  its  coming,  and  so  has  not  made  preparation 
for  the  disposal  of  the  food.  The  nose  does  not  smell  the  food,  and 
the  mouth  does  not  chew  and  taste  the  food  sufficiently  to  excite  the 
stomach  to  set  up  the  general  process  of  digestion.  Numerous  simi- 
lar facts  might  be  presented,  showing  very  clearly  the  close  relation 
existing  between  the  various  digestive  processes  and  intellectual  states. 
Long  observation  and  experience  prove  that  it  is  far  better  for  a  per- 
son to  eat  what  is  set  before  him,  asking  no  questions,  either  for  con- 
science' sake  or  the  stomach's  sake,  than  to  take  food  in  an  anxious 
and  worried  state  of  mind,  questioning  or  doubting  the  nutritive  value 
of  the  food  to  be  eaten.  Many  a  chronic  dyspeptic  maintains  his  dis- 
order by  keeping  his  stomach  in  a  sort  of  "stage  fright,"  through  the 
concentration  of  his  attention  upon  this  portion  of  his  anatomy  during 
the  whole  digestive  process.  —  Good  Health. 


CHAPTER   XV 
STIMULANTS  AND  NARCOTICS 

480.  In  the  year  1881  Dr.  Hammond,  a  New  York  phy- 
sician, made  the  assertion  that  a  forty  days'  fast  was  a 
physical  impossibility.     This  led  Dr.  Tanner,  a  Minnesota 
physician,  to  attempt  such  a  feat.     He  arrived  in  New  York 
weighing  184  pounds.     He  was  six  weeks  making  arrange- 
ments for  his  fast,  and  when  he  began  his  experiment,  his 
weight  was  157^  pounds.     He  weighed  \2\\  pounds  on 
the  day  his  fast  ended.     He  had  therefore  lost  36  pounds 
since  his  fast  began.     The  first  thing  he  ate  to  break  his 
fast  was  a  watermelon,   swallowing  only  the  juice.     Dr. 
Hammond  came  out  in  a  card  in  the  New  York  papers  de- 
claring that  he  believed  the  fast  had  been  fairly  conducted. 

481.  Succi,  an  Italian,  successfully  accomplished  a  fast 
of  50  days  in  London,  being  likewise  constantly  watched  to 
make  sure  of  his  fasting.     There  is  reported,  on  good  au- 
thority a  case  of  an  insane  person  who  suddenly  became 
possessed  by  the  idea  of  taking  no  food,  and  who  took  60 
days  to  starve  himself  to  death.     Long  fasts  are  a  great  in- 
jury to  the  body,  no  doubt,  but  what  can  we  learn  from 
such  experiences  ?     Certainly  it  shows  the  wisdom  with 
which  we  are  made,  certainly  that  our  physical  organization 
is  very  provident. 

482.  Once  some  miners  were  shut  in  by  caving  of  part 
of  the  mine.     But  unlike  the  cases  mentioned  above  they 
were  without  water  as  well  as  food..    When,  by  digging, 
the    rescuers    reached    them,    seven    days    after,    several 
were  still  found  alive,  although   most  of  them  had  suc- 

268 


STIMULANTS  AND  NARCOTICS  269 

cumbed.  The  miners,  no  doubt,  had  nourishment  in  their 
bodies  for  some  weeks  more  of  life,  but  the  necessary  sol- 
vent in  the  form  of  water  was  lacking  to  dissolve  it  and 
bring  it  within  the  reach  of  the  cells  most  needing  it. 

483.  A  Fact  of  Immense  Importance.  —  This  fact  concern- 
ing the  amount  of  nourishment  stored  in  the  human  body 
(in  one  case  a  two  months'  supply  !)  is  one  of  the  most 
stupendous  facts  with  which  the  science  of  physiology  has 
to  deal,  and  it  should  be  borne  in  mind,  or  we  may  greatly 
deceive  ourselves  about  some  very  simple  matters. 

484.  Foolhardiness.  —  Did  you  ever  get  so  tired  that  you 
had  to  give  up  and  stop,  however  much  you  would  have  liked 
to  continue  at  work  or  play  ?    To  rest  was  the  wise  thing  to 
do.    Now,  although  you  learned  from  physiology  how  much 
energy  you  have  stored  up  within  your  frame,  you  should  not 
on  that  account,  be  tempted  to  go  on  until  you  almost  break 
down.     Probably  you  know  people  who  are  conceited  about 
their  bodies  and  say  they  are  made  of  cast  iron ;  nothing 
can  hurt  them.     Did  you  ever  know  anybody  who  was  con- 
ceited about  his  mind  and  thought  he  was  very  bright  ? 
It  is  just  as  foolish  to  be  conceited  about  the  body. 

485.  A  Blessing  in  Disguise.  —  It  is  a  very  wise  arrange- 
ment that  under  ordinary  conditions  we  cannot  get  at  the 
surplus  energy  we  have.     We  are  compelled  to  be  provi- 
dent, as  it  were ;  yet  stimulants  and  narcotics,  by  irritating 
the  cells,  will  cause  them  to  expend  some  of  this  reserve 
energy  ;  they  will  enable  man  to  get  at  this  precious  store 
which  he  should  save  for  emergencies,  such  as  a  spell  of 
sickness  when  he  cannot  digest  food,  or  when  he  is  making 
some  mighty  effort.    This  reserve  energy  will  enable  him  to 
undergo  some  trying  ordeal  successfully. 

Did  you  ever  know  of  a  weak  sick  man  who  had  eaten 
very  little  for  weeks,  yet  was  so  powerful  that  it  took 
several  strong  men  to  hold  him  ?  This  sometimes  hap- 
pens in  the  case  of  sick  men  who  are  delirious  and 


2/0  ELEMENTS   OF  PHYSIOLOGY 

crazed  with  pain  and  with  the  poisons  formed  in  their 
bodies  during  illness.  But  the  delirious  mania  often  uses  up 
the  little  energy  left  and  costs  people  their  lives. 

486.  The  Meaning  of  Fatigue,  the  Blues,  etc.  —  Suppose 
you  are  tired  or  worked  down.     The  fatigue  depresses  you, 
and  you  feel  discouraged.     What  ought  you  to  do  ?     Why, 
rest,  of  course,   and  you  will  soon  feel  all   right  again. 
This  seems  very  simple,  yet  some  people  will  not  do  this 
way,  but   take  an   alcoholic  beverage  or  tobacco,  which 
will  keep  them  from  feeling  tired  when  they  are  tired. 
If  you  have  been  working  hard  preparing  for  examinations, 
or  gathering  hay,  or  in  attending  to  some  important  busi- 
ness, or  have  been  under  the  excitement  of  some  pleasure 
trip,  and  feel  blue  and  worn  out,  then  bear  the  result  like 
a  man,  or  like  a  true  boy  or  girl,   as  the  case  may  be. 
Giving  up  for  a  while,  or  "  toughing  it  out "  with  the  blues, 
or  losing  a  little  time  from  business,  will  not  hurt  you  but 
will  make  you  strong,  while  a  stimulant  will  leave  you  less 
of  a  man  than  before. 

487.  There  is  only  one  source  of  energy  for  man's  body, 
and  that  is  the  union  of  food  and  oxygen.     He  must  get 
his  energy  from  the  same  source  that  the  engine  does,  and 
that  is  from  his  food,  which  serves  as  fuel,  and  the  oxygen 
that  burns  it.     The  millions  of  little  workers,  the  cells,  will 
store  up  food  within  themselves  and  get  rid  of  the  ashes 
and  refuse,  and  the  pure,  sound  body  will  be  ready  for 
work  again. 

488.  Alcohol  is  a  Whip  or  a  Spur.  —  It  is  to  get  strength 
out  of  a  man,  not  to  put  it  in.      When  a  person  feels 
that  he  is  all  tired  out   and   his   nerves   are  weak,  and 
takes  a  stimulant,  it  is  the  same  as  if,  when  his  horse  shows 
signs  of  breaking  down,  he  should  lash  him  with  a  keen 
whip,  or  pierce  him  with  a  sharp  spur,  instead  of  letting 
him  rest.     Many  a  fine  horse  under  the  sting  of  the  whip 
has  been  spoiled  in  a  few  hours,  and  many  a  man  has  been 


STIMULANTS  AND  NARCOTICS  2? I 

physically  ruined  for  life  by  overworking,  goaded  on  by 
alcohol,  during  one  season  of  business  rush. 

489.  How  Stimulants  arouse  Energy. — You  remember 
those  wonderful  little  one-celled  animals,  the  amebas.     If 
poison  is  brought  near,  they  will  try  to  escape  it.    They  also 
throw  out  the  impurities  generated  by  their  own  life  pro- 
cesses.    If  anything  touches  one  roughly,  it  will  draw  back 
from  the  danger.      Likewise,  if  a  man  takes  poison,  such 
as  alcohol  or  tobacco,  into  his  body,  the  cells  will  try  to 
throw  it  off.     The  heart,  although  it  may  be  already  tired, 
goes   to   thumping   anew,  secretions   are   poured   out  by 
the  cells  to  dilute  and  weaken  the  poison,  and  the  great 
activity  excited  diverts  the  man  from  noticing  his  fatigue, 
and  makes  him  think  the  poison  has  given  him  renewed 
strength.     It  is  the  same  as  if  he  thought  the  whip  instead 
of  the  oats  gave  the  horse  strength.     The  horse,  like  the 
cells  of  the  body,  is  only  trying  to  avoid  something  harm- 
ful, and  like  them,  he  uses  up  his  strength  in  so  doing. 
After  a  while  he  will  be  very  stiff  and  tired.     There  is  no 
artificial  stimulant  that  does  not  cause  a  reaction.     The 
stronger  the  stimulant,  the  worse  the  poison.     Strychnine 
is  one  of  the  deadliest  poisons  known,  and  also  one  of  the 
most  powerful  stimulants.     If  an  animal  is  given  strych- 
nine, its  nerve  tissue  is   sometimes  reduced  to  such  an 
irritable  condition  that  a  loud  sound,  or  merely  touching 
any  part  of  it,  will  throw  every  muscle  of  its  body  into  a 
spasm. 

490.  Natural  Stimulants  do  not  cause  depression.     The 
chief  natural  stimulants  are  cold  air,    sunlight,  pure  air, 
physical  exercise,  interest,  joy,  and  other  emotions.     A  deep 
breath  of  pure  air  is  a  better  stimulus  than  a  glass  of  beer ; 
climbing  a  hill  or  sawing -a  log  of  wood  will  make  the  blood 
flow  faster  than  alcohol ;  a  pleasant  talk  with  a  friend  is  a 
better  sedative  than  a  cigar ;  a  cold  day  will  steady  the 
nerves  better  than  an  opiate ;  a  trust  that  a  good  Power 


2/2  ELEMENTS   OF  PHYSIOLOGY 

rules  over  all  will  drive  away  worry  quicker  than  cocaine ; 
a  cold  bath  will  bring  steadier  nerves  than  coffee ;  a  cold 
wind  will  give  a  better  appetite  than  food  soured  with 
vinegar  or  hot  with  pepper.  Natural  stimulants  do  not 
produce  a  reaction  because  they  do  not  excite  the  body  to 
an  injurious  degree,  nor  cause  the  energies  to  be  consumed 
beyond  the  danger  point.  Persons  who  go  through  life 
under  the  stimulus  of  these  natural  blessings  have  sound 
steady  nerves  and  clear  brains.  They  do  not  have  to  take 
anything  "  to  quiet  their  nerves." 

491.  Some  people  are  coffee  topers  and  tea  topers.     It  is 
a  mistake  to  say  these  things  quiet  the  nerves.     Who  is  so 
nervous  as  the  old  lady  who  drinks  frequent  cups  of  tea  to 
quiet  her  nerves .?     It  is  the  tea  that  is  making  her  nerves 
unsteady.      Some   people    unaccustomed   to   tea   will   lie 
awake  most  of  the  night,  wearing  out  their  energies  by 
sleeplessness  if  they  drink  only  one  cup  of  it. 

492.  It  is  easy  to  understand  how  a  person  sitting  up 
with  a  friend  who  is  dangerously  ill  will  take  tea  or  coffee 
to  keep  him  wide  awake.     If  he  has  some  great  duty  to 
perform,  or  trust  imposed  upon  him  that  will  soon  be  over, 
there  may  possibly  be  some  reason  in  stimulating  his  ac- 
tivities, even  if   he  must  suffer  reaction  and  depression 
thereafter.     But  why  one  will  habitually  disturb  his  body 
with  narcotics,  such  as  alcohol,  tobacco,  or  even  mild  nar- 
cotics, such  as  tea  and  coffee,  so  as  always  to  keep  his  vital 
force  and  reserve  energy  at  a  low  ebb,  is  difficult  to  under- 
stand.     It  can  only  be  explained   by  ignorance   of   the 
fundamental  laws  of  his  being. 

493.  The  Use  of  Natural  Stimulants.  —  Man's  body  was 
beneficently  designed  to  keep  a  large  amount  of  energy 
stored  up,  so  that  he  can  feel  conscious  of  his  power  and 
go  through  life  buoyantly  and  happily,  and  prepared  for 
all  emergencies,  —  the  highest  being  in  the  world  that  he 
inhabits.     He  is  in  a  world   full   of   interest.     Delicious 


STIMULANTS  AND  NARCOTICS  2/3 

fruits  and  nutritious  nuts  and  grains  abound  to  awaken 
and  satisfy  his  appetite.  The  bright  sun  not  only  shines 
upon  his  skin,  but  deep  into  it,  and  stimulates  the  cells ; 
the  fresh  breezes  striking  his  nerves,  start  currents  cours- 
ing through  his  body.  The  oxygen  penetrates  to  every 
cell,  purifying  and  awakening  to  life.  The  pleasure  of 
association  with  his  fellow-creatures,  and  various  other 
pleasures,  arouse  him  to  do  his  part  in  the  world.  There 
is  no  need  to  seek  in  the  jungle  for  some  bitter  berry,  or 
among  the  weeds  for  some  nauseating  leaf,  or  among  de- 
caying apples  or  grapes  or  fermenting  grain  for  a  burning 
and  revolting  liquid  in  order  to  stir  his  being  to  action. 
He  lives  the  life  for  which  his  body  was  designed. 

494.  How  Man  comes  to  deprive  himself  of  Natural 
Stimulants.  —  But  suppose  he  becomes  wise  and  wishes  to 
improve  on  the  simple  blessings  of  life.  He  must  stay  in 
the  house  continually  in  order  to  transact  much  business 
and  make  money,  or  to  acquire  precious  wisdom  in  musty 
books.  He  must  curtain  off  the  sunshine  for  fear  it  will 
cause  his  fineries  to  fade ;  must  shut  out  the  air  and  keep 
in  the  dust.  His  great  knowledge  tells  him  that  cool 
draughts  are  dangerous  upon  a  skin  made  delicate  with  a 
load  of  clothing.  The  joys  and  stimulus  of  friendship  and 
of  unreserved  communion  with  his  fellows  leave  him,  as  he 
narrows  his  view  and  fixes  his  gaze  on  some  selfish  object. 
The  voluntary  motions  of  his  body  are  confined  mostly  to 
his  fingers  and  his  tongue,  as  he  writes  and  talks  in  trans- 
acting business,  for  he  is  too  proud  to  walk,  or  to  work  with 
his  hands,  and  thus  the  circulation  throughout  his  body 
becomes  sluggish.  His  natural  appetite  becomes  weak  and 
would  regulate  the  amount  of  food  according  to  the  narrow 
incomplete  life  he  is  living,  but  he  gets  an  artificial  one, 
with  sour  or  peppery  seasonings,  and  the  half-digested  food 
makes  poison  for  his  blood.  His  nerves  become  weak,  his 
wit»  blunted,  his  body  sluggish  and  depressed, 
T 


274  ELEMENTS   OF  PHYSIOLOGY 

495.  What  this  leads  to.  —  He  adopts  the  use  of  poison- 
ous stimulants  that,  in  the  effort  to  rid  themselves  of  the 
poisons,  the  cells  may  have  an  incentive  to  activity,  and 
the  awakening   of  his   weakening  system   may  give  him 
the  feeling  of  power  and  enable  him  to  stick  to  his  work 
and  his  unhealthy  life.     Coffee,  tea,  tobacco,  wine,  beer, 
whisky,    form   a   gradual   progression   toward  ruin.      He 
may  feel  worn  out,  but  a  strong  cigar,  sending  the  poison- 
ous fumes  of  nicotine  into  his  delicate  thin-walled  lungs, 
will  so  set  his  nerves  on  fire  that  he  feels  vigorous,  and 
says,  "  What  nerve-strength  comes  from  tobacco  !  "     For 
it  seems  we  feel  vigorous  only  when  we  are  expending 
energy  very  rapidly,  even  if  the  store  of  energy  is  nearly 
exhausted.     He  feels  discouraged  and  weak,  and  takes  a 
glass   of    whisky;   this   disturbance   to   the   system,  with 
the   great   amount  of  energy  expended  in  getting  rid  of 
it,  makes    him  think  he  has  had  a  sudden   accession  of 
strength,  for  he  forgets   the  work   that   the   faithful   old 
stomach  has  been  doing  in  storing  away  food  in  the  cells 
(alcohol  is  never  stored  in  the  cells,  but  all  foods  are) ;  he 
forgets  the  industrious  lungs  and  the  oxygen  they  have  been 
storing  in  the  blood  and  cells.     He  is  like  the  man  who  has 
piled  up  money  in  a  bank  and  draws  it  out  with   checks 
and  says  :    "  What  a  wonderful  thing  a  check  is  !      How 
valuable  is  my  check  book  !  "     But,  if  he  were  to  lose  the 
check  book,  the  bank  would  give  him  another  for  nothing. 
The  check,  when  written,  is  only  a  sign  that  money  must 
come  out  of  the  bank,  and  the  alcohol  when  taken  into  the 
body  is  only  a  sign  that  strength  must  come  out  of  the  body 
in  expelling  the  enemy.     No  wonder  the  man  has  a  bad 
headache  the  next  morning. 

496.  Spendthrifts  of  Vitality.  —  Did  you  ever  know  per- 
sons who  could  not  keep  any  money  or  property  ?      Dollars 
seem  to  burn  holes  in  their  pockets.     They  do  not  know 
how  to  economize  when  funds  are  low,  but  are  always  get- 


STIMULANTS  AND  NARCOTICS  2/5 

ting  in  debt  and  borrowing,  and  mortgaging  their  crops  or 
their  stock  or  their  homes.  There  are  many  such  people, 
and  there  are  just  as  many  who  cannot  store  up  any  of  that 
precious  capital  consisting  of  bodily  health  and  strength.  If 
they  feel  buoyant  and  strong,  they  will  not  economize  their 
strength,  but  work  or  go  until  they  are  worn  out,  and  then 
take  tobacco  or  alcohol  to  deaden  the  tired  feeling.  If  a 
man  is  weary,  it  is  not  to  his  interest  to  feel  rested  until  he 
is  rested.  Such  feelings  are  a  cheating  of  nature,  a  break- 
ing down  of  the  protective  barriers  around  life's  citadel. 
Such  a  one  deceives  himself.  One  who  deceives  another 
is  called  a  liar ;  one  who  habitually  deceives  himself  brings 
the  same  destruction  upon  himself  as  the  fool. 

497.  C.  F.  Hodge,    Professor   of    Physiology  in  Clark 
University,   made    a    series    of    experiments    upon    four 
kittens  and  four  spaniels.     Moderate  non-intoxicant  doses 
of  alcohol  were  given  daily  to  two  of  each. 

(Dogs  could  be  killed  in  a  few  minutes  or  a  few  days  or 
months  by  sufficiently  large  doses  of  alcohol.  While  such 
experiments  might  have  some  interest  to  toxicology,  they 
could  not  have  much  to  physiology.) 

498.  At  the  end  of  ten  days,  the  two  kittens  dosed  with 
alcohol  took  severe  colds.     Up  to  this  time,  purring  and 
playfulness  had  been  disappearing  from  their  lives.     They 
were  dwarfed  in  growth  to  63  and  39  per  cent,  respec- 
tively, as  compared  with  the  others. 

499.  Of  the  two  pairs  of  spaniels,  the  pair  treated  with 
alcohol  weighed  less,  and  developed  only  71  and  57  per 
cent  of  the  activity  of  the  other  pair,  as  shown  by  the  pe- 
dometer.    The  dogs  treated  with   alcohol  also  developed 
strange  symptoms  of  timidity  and  fear,  suggesting  the  ter- 
rible fears  of  delirium  tremens  and  alcoholic  insanity. 

500.  In  Dr.   Hodge's  opinion   the    experiments   above 
described  have  direct  bearing  on  the  question  of  the  effect 
of  alcohol  on  the  human  system.     The  experiments  proved 


276  ELEMENTS  OF  PHYSIOLOGY 

that  alcohol  causes  depression  of  activity.     For  man  the 

highest  aim  is  to  develop  useful  activity,  the  will,  the  deter- 
mination to  do  as  much  of  the  world's  necessary  work  as 
he  is  capable  of  doing,  and  a  sound,  vigorous  body  to 
enable  him  to  carry  out  such  determination.  It  is  of  the 
utmost  importance,  therefore,  that  we  understand  the  con- 
ditions of  our  physical  systems  under  which  this  great  end 
can  best  be  attained. 

501.  In  no  other  country  are  there  so  many  people  who 
refrain  from  using  intoxicating  liquors  as  in  the  United 
States.     Many  forces  have  united  to  bring  about  this  con- 
dition, chiefly  temperance  organizations,  ministers,  teach- 
ers, and  the  newspapers.    To  a  greater  extent  than  in  other 
countries  also  intemperance  has  been  driven  out  from  the 
upper  classes  by  the  force  of  public  opinion ;  it  is  no  longer 
fashionable.     Temperance  has  gained  in  spite  of  the  fact 
that  the  climate  of  the  United  States  tends  strongly  to 
cause  the  excessive  use  of  alcoholic  liquors. 

502.  A  Knowledge  of  Physiology  is  a  great  help  in  pro- 
moting the  cause  of  temperance.     All  who  acquire  such 
knowledge  are  the  better  able  to  contribute  their  share  to 
the  good  work.     There  can  be  no  doubt  that  the  use  of 
alcohol  is  steadily  diminishing  as  the  people  learn  more 
of  physiology,  especially  of  the  true  nature  of  alcohol  and 
of  its  effects  on  the  system.     General  education  also  fights 
against  intemperance,  as  few  people  interested  in  gaining 
knowledge    care    to    indulge    to    excess    in    intoxicating 
drinks. 

503.  Why  the  Drinker   increases   his   Dram. — Tanner 
and  Succi   have  proved  that   for   the  ordinary   man   the 
energy  stored  up  is  sufficient  for  many  weeks  of  life  with- 
out replenishing  it  by  taking  one  morsel  of  food.     When  a 
man  begins  to  drink,  the  energy  of  his  body  may  be  of 
large  amount,  and  a  small  amount  of  alcohol  suffices  to 
stimulate    and   exhilarate   him.      But   a   few   stimulations 


STIMULANTS  AND  NARCOTICS 

serve  to  cause  a  large  part  of  his  energy  to  be  con- 
sumed, and  a  larger  amount  of  stimulant  is  therefore 
required  to  arouse  to  action  the  exhausted  cells.  Thus 
it  goes  on ;  the  more  he  abuses  his  system  by  arousing  it 
to  expel  the  poison,  the  less  energy  he  has  left  and  the 
more  difficult  it  is  to  arouse.  The  nearer  worn  out  the 
tired  horse  is,  the  sharper  must  it  be  lashed  to  keep  it  go- 
ing. The  habitual  user  of  alcohol  is  not  only  its  slave,  but 
a  slave  that  is  constantly  being  drawn  closer  and  closer 
within  its  relentless  clutches.  The  energy  of  the  cigarette 
user  sinks  to  a  lower  and  lower  ebb,  and  he  constantly 
increases  the  nicotine  in  order  to  arouse  it. 

504.  Inebriate  Cures.  —  These  are  sometimes  successful, 
but  are  usually  failures.  What  makes  the  cure  of  the 
drunkard  so  difficult  is,  that  he  is  not  really  willing  to 
undergo  the  pain  and  trouble  necessary  to  stop.  During 
some  unselfish  moments,  and  when  he  realizes  more  than 
usual  the  destruction  that  dissipation  is  bringing  upon  him, 
he  may  truthfully  desire  to  make  any  sacrifice  to  free  him- 
self and  become  restored  to  manhood,  but  so  ruinous  has 
been  the  effect  of  alcohol  upon  his  moral  nature,  that  such 
moments  do  not  last  long,  and  when  the  first  promptings  of 
the  appetite  return,  he  falls,  and  would  sell  the  roof  from 
over  the  heads  of  his  wife  and  children  to  get  money  to 
gratify  his  thirst.  The  inebriate  cures  base  their  method 
upon  convincing  him,  by  secretly  adding  a  nauseating  dose 
to  his  drink,  or  by  some  other  plan,  that  alcohol  has  turned 
against  him  and  no  longer  gives  him  pleasure,  and  he  be- 
comes convinced  that  he  must  stop,  and  willing  to  try  to 
quit.  The  best  way  to  quit  alcohol,  opium,  tobacco,  or 
other  narcotics,  is  by  a  straightforward  resolve  to  do  so,  and 
by  stopping  at  once.  While  the  poison  is  being  removed 
from  the  body,  the  nerves  are  so  irritable  that  the  least 
sound  or  change  of  temperature  may  bring  torture  to  the 
patient,  and  sometimes  it  is  necessary  to  keep  him  in  a  quiet 


278 


ELEMENTS   OF  PHYSIOLOGY 


room,  submerged   in  a  bath  just  the  temperature  of  the 

body,  for  several  days  at  a  time. 

505.   The  Discovery  of  Alcohol.  —  A  long  time  ago  learned 

men  called  alchemists  (the  predecessors  of  the  chemists  of 

the  present  day)  be- 
lieved that  they  could 
succeed  in  discover- 
ing the  elixir  of  life, 

•j  *f  A  the  water  of  perpetual 

youth.  In  the  year 
1000,  an  Arab  alchem- 
ist, while  seeking  the 
elixir  of  life,  discov- 
ered alcohol.  Of 
course  it  had  existed 
long  before,  wherever 
fermentation  of  sugar 
took  place,  and  had 
been  drunk  in  wine, 
in  which  it  occurs  in 
a  diluted  condition. 
But  this  alchemist  suc- 
ceeded in  distilling,  or 
evaporating  and  con- 
densing, it  from  the 
water  of  the  wine. 
When  he  first  drank 
alcohol,  he  felt  that 
he  had  some  new  and 
strange  liquid  which 
he  believed  would 
prove  to  be  the  water 


FlG.  191.  —  An  illustration  of  the  nerve  branches 
and  fibers  in  a  case  of  alcoholic  insanity.  The 
patient  died  of  this  disease  and  when  the  nerve 
fibers  were  examined  under  the  microscope, 
they  were  shown  to  be  swollen  and  broken 
down  in  the  manner  illustrated  in  the  drawing. 
The  swellings  of  the  nerve  fibers,  as  seen  in  this 
illustration,  are  characteristic  effects  produced 
by  alcohol,  and  are  usually  seen  in  the  brain 
of  those  dying  from  alcoholic  insanity. 


of  life.  But  experi- 
ence soon  showed  that  the  use  of  it,  instead  of  giving 
freedom  from  death  and  perpetual  youth,  shortened  life 


STIMULANTS  AND  NARCOTICS 


279 


instead.  Yet  the  name  "water  of  life"  is  still  the  term 
used  for  brandy  in  the  French  language,  and  one  may 
see  in  immense  letters  on  a  wall  at  the  end  of  a  street  near 
the  University  of  Paris,  the  suggestive  sign,  Dfyot  de  V Eau 
de  Vie,  "  Storehouse  of  the  Water  of  Life." 

506.  Truly  the  Bible  gives  the  heart  of  the  matter  when 
it  speaks  of  wine  and  those  who  are  deceived  thereby ;  for 
the  deception  of  a  part  of 

mankind  has  been  com- 
plete. The  use  of  narcotics 
has  been  pronounced  a  blot 
upon  civilization,  and  phys- 
iologists and  sociologists 
have  united  in  declaring 
that  alcohol  ranks  ahead 
of  war  and  other  evils  as 
the  greatest  obstacle  to 
civilization  and  the  happi- 
ness of  mankind,  that  exists 
in  the  world. 

507,  Of  all  the  Diseases 
that  have  been  named  as 
being  caused  by  alcohol,  no 
one  person  ever  has  more 

than  a  small  part.  Those  of  the  organs  that  are  weakest  give 
way  first,  and  death  results  before  the  others  are  attacked. 
The  stomach  may  become  so  ulcerated  that  it  cannot  even 
bear  water,  which  throws  the  victim  into  a  spasm.  In  such 
a  case,  he  will  probably  die  in  delirium  tremens,  a  condi- 
tion of  horrible  temporary  insanity. 

The  body  seems  in  some  instances  to  become  used  to 
the  moderate  use  of  poisons  such  as  nicotine  and  alcohol, 
and  in  outward  appearance  to  escape  serious  harm. 
For  one  that  apparently  escapes,  many  are  destroyed.  We 
sometimes  see  very  old  men  that  have  smoked  tobacco  for 


FIG.  192.  —  This  figure  shows  four  nerve 
cells  from  the  brain  of  a  man  who  died 
of  alcoholic  insanity.  It  will  be  noticed 
that  the  body  of  the  cells  and  the  nerve 
fibers  are  broken  up  and  degenerated. 
The  changes  shown  in  Fig.  191  are 
the  more  severe  changes,  and  represent 
complete  destruction  of  the  nerve  tissue. 


280  ELEMENTS   OF  PHYSIOLOGY 

fifty  years.  But  if  such  men  had  begun  when  young 
boys,  or  had  used  cigarettes  and  inhaled  the  smoke,  they 
would  be  even  fewer  than  they  are. 

508.  Review  of  Effects  of  Alcohol.  —  Give  the  effect  of 
alcohol  upon  (i)  the  skin  and  bones;  (2)  the  muscles;  (3) 
the  stomach;   (4)  the  liver;   (5)  the  circulation;   (6)  the 
respiration ;  (7)  the  nervous  system.     (8)  Discuss  whether 
alcohol  is  a  food. 

509.  Drug  Habits  are  growing  with  such  rapidity  that  it 
is  a  question  whether  the  drug  fiend  will  not,  before  long, 
be  as  common  as  the  drunkard.     The  physician  meets  few 
more  pitiable  sights   than  that  presented  by  the  typical 
morphine  or  cocaine  fiend.     The  evil  is  invading  all  classes 
of  society,  including  numbers  of  physicians.     Many  patent 
medicines,  cough  cures,  headache  powders,  colic  cures,  etc., 
contain  morphine.     It  is  a  deep-seated  fallacy  existing  in 
the  minds  of  the  masses,  that  they  can  violate  with  im- 
punity the  laws  of  health  and  life  which  have  been  insti- 
tuted by  infinite  power  and  wisdom,  and  then  dodge  the 
unpleasant  consequences  by  simply  swallowing  a  few  drops 
of  some  sedative  or  anodyne.     About  $200,000,000  worth 
of  patent  nostrums  are  annually  disposed  of.     The  aver- 
age  invalid   demands    something    more   substantial   than 
extravagant  claims.      As   there  is  no  drug   that  will   so 
effectually  smother,  for  a  time,  the  cries  of  an  outraged 
nerve  as  some  form  of  opium,  and  as  there  is  no  drug  that 
is  so  deceptive  a  stimulant  as  cocaine,  these  two  are  most 
often  found  in  these  quack  remedies.     They  assist  in  secur- 
ing convincing  testimonials  as  to  the  wonderful  curative 
power,  which  is  supposed  to  be  identical  with  the  relief 
from  pain  furnished.     The  invalid  soon  learns  to  buy  the 
active  agent  in  the  nostrum  in  its  pure  form,  and  this  often 
seals  his  fate. 

510.  Subjects  for  Compositions.  —  Cooking.    Health  and 
the  Home.      The  Body  subject  to  Law.     Improved  Dress. 


STIMULANTS  AND  NARCOTICS  28 1 

Some  of  my  Observations  and  Experiences  from  the  Stand- 
point of  Physiology.  Tight  Shoes.  An  Incident  from 
Life.  Physical  Education  compared  with  Mental.  Hy- 
giene of  the  Schoolroom.  Extremes  in  Hygiene.  Microbes. 
Health  and  Country  Life.  Looking  Back.  Looking 
Ahead.  Health  and  City  Life.  The  Right  Way  the 
Easiest. 


PART   IV.      HOW   THE    BODY   IS   CON- 
TROLLED 

CHAPTER  XVI 

THE  NERVOUS   SYSTEM 

511.  Function   of  Nervous  System.  —  The  ameba   and 
other  one-celled  animals  need  no  nervous  system,  but  the 
larger  animals,  consisting  of  a  colony  of  cells,  as  it  were, 
need  a  means  of  communication  between  the  cells,  in  order 
that  their  life  may  be  harmonious.   Robinson  Crusoe  could 
not  have  used  a  telephone  or  a  post  office  system,  but  a 
number  of   individuals  living  together  and   practicing  a 
division  of  the  labor  of  the  community  for  their   mutual 
advantage,  are  compelled  to  communicate  with  each  other 
in  order  to  make  their  necessities  known.     The  lowest  of 
the  many-celled  animals,  such  as  the  sponges,  have  no  cells 
specially   set   apart  for  carrying    messages   between  the 
cells,  but  each  cell  passes  the  impulses  it  receives  to  its 
neighbor  cell.     This  will  do  for  a  small  and  simple  com- 
munity of  cells,  but  a  larger  community,  like  one  of  the 
higher  animals,  possesses  certain  cells,  called  nerve  cells, 
whose   chief  function    is  to  keep  up  the  communication 
between  the  cells.     In  the  chapter  on  the  master  tissues 
you  learned  that  the  nerve  cells  did  this  by  means  of  long 
branches,  which  in  some  cases  are  several  feet  long. 

512.  Communication  is  not  All  that  is  necessary.  —  Did 
you  ever  see  a  crowd  of  people  at  a  fire  when  a  neighbor's 
house  was  burning  ?     Everybody  ran  about,  yet  very  little 
was  done.    Everybody  shouted  orders  which  nobody  obeyed. 
But  on  the  arrival  of  the  chief  of  the  fire  department  or 
the  head  of  a  fire  company,  who  had  had  experience  in 

282 


THE  NERVOUS  SYSTEM  283 

the   control  of   men  fighting  a   fire,  the  scene  changed ; 
valuable  property  was  saved,  and  the  fire  was  stopped. 

513.  Every  community  has  certain  deliberative  and  con- 
trolling bodies ;  these  may  be  a  board  of  aldermen,  a  court 
of  justice,  a  legislature,  or  a  congress.       In  a  similar  way 
the  great  number  of  individual  cells  which  make  up  the 
human  body  must  be  controlled  by  some  central  power, 
or  they  will  not  work  in  harmony  ;     nothing  will  be  accom- 
plished,   but  a  state  of  anarchy   and   helplessness  called 
disease,  will  follow.     The  seat  of  this  central  controlling 
power  is  believed  to  be  located  in  the  brain. 

514.  Coordination.  —  The  nerve  cells  receive,  modify,  and 
send  out  impulses.      By  these   three  kinds  of  acts  the  ner- 
vous   system    accomplishes    what   is    called  coordination. 
This  term  signifies  not  only  that  the  cells  work  together  at 
the  same  time,  but  that  they  work  together  as  a  part  of  a 
plan  for  the  accomplishment  of  some  definite  result.     Sup- 
pose that  a  man  sees  a  bright   dollar   in    the    road   and 
picks  it  up.     In  order  that  he  may  do  this,  the  cells  re- 
ceiving  through  the  optic   nerve  the   impression  of  the 
shining   coin  must   be  in    communication,  either  directly 
or  indirectly,  with  the  muscles  of  the  hand ;  and  that  the 
hand  may  reach  the  coin,  the   muscles  of  the  arms,  legs, 
trunk,  head,  and  neck  must  act  together.    Even  the  heart 
and  respiratory  muscles  must  modify  their  action  somewhat 
to  suit  the  movement. 

515.  Other  Organs  besides  Muscles  must  be  coordinated. 
—  Suppose  a  boy  sees  a  large  red  apple.     He  notices  the 
odor  which  tells  him  that  it  is  ripe,  and  his  "  mouth  waters  " 
for  it ;  that  is,  the  salivary  glands  begin  to  work,  even  before 
he  puts  the  apple  to  his  mouth.      The  chewing  and  swal- 
lowing, the  secretion  and  peristalsis  in  the  digestive  organs, 
are  all  carried  on  under  the  control  of  impulses  that  reach 
them  through  the  nerves.      Without   these  impulses,   the 
salivary  glands  would  not  work  when  the  mouth  was  chew- 


284 


ELEMENTS   OF  PHYSIOLOGY 


ing  the  food ;  the  dry  food  would  stick  to  the  esophagus 
and  have  to  be  washed  down  with  water;  the  gastric  juice 

would  not  be  secreted  at  just 
the  right  time;  the  food  would 
ferment  in  the  stomach,  and 
the  person  would  soon  be  ill. 
516.  Nerve  Cells  (Fig.  193). 
-You  learned  when  studying 
the  master  tissues  that  the  ner- 
vous system  consists  of  nerve 
cells  with  their  branches,  called 
nerve  fibers.  Nerve  cells  are 
microscopic  bits  of  protoplasm, 
like  other  cells,  yet  they  are 
remarkable  among  animal  cells 
for  their  large  size.  Some  of 
the  cell  bodies  in  the  spinal 
*cord  are  so  large  as  to  be  almost 
visible  to  the  unaided  eye,  and 
have  branches  leading  from 
the  cord  to  the  hand  or  foot. 
Each  cell  contains  a  nucleus, 
within  which  is  a  nucleolus 
(Fig.  193).  Nerve  cells  are 
the  most  remarkable  in  the 
body  for  irregularity  of  shape ; 
some  of  them  have  so  many 
branches  that  they  have  a  star- 
like  appearance. 

.  —  Branched  Nerve  Cell  from 

Spinal  Cord.  517.  The  Dendrons  of  a  nerve 

a,  axis  cylinder  or  axon;  bt  dendrons;  c,    cell    are    the    treelike     branches 

which  bring    impulses   to  the 

cell  (Fig.  193).  Through  the  dendrons  the  cell  may  be  in 
communication  with  numerous  other  cells.  'A  branch  of 
one  cell  does  not  join  the  branch  of  another  cell.  It  has 


THE  NERVOUS  SYSTEM 


285 


not  yet  been  settled  by  physiologists  whether  the  ends  of 
the  dendrons  of  communicating  cells  actually  touch. 

518.  The  Axis  Cylinder,  or  Axon.  —  In  most  of  the  fully 
developed  nerve  cells,  one  of  the  branches  is  very  greatly 
prolonged  as  a  fine  thread  of  protoplasm, 

which  becomes  the  core  of  a  nerve  fiber 
(Fig.  193).  Every  nerve  fiber  has  such  a 
core.  In  most  of  them  this  central  thread 
of  protoplasm  becomes  covered  with  two 
coats ;  an  outside  protective  coat  forms 
a  tube,  called  the  connective  sheath :  and 
between  the  walls  of  this  tube  and  the 
central  thread  is  a  coat  of  semiliquid,  fatty 
substance  called  the  medullary  sheath, 
which,  shining  through  this  outer  sheath, 
gives  a  silvery  white  appearance  to  the 
fiber.  Such  fibers  are  called  medullated 
fibers,  or  white  fibers  (Fig.  194).  Some 
fibers  lack  the  medullary  sheath,  and  are 
called  non-medullated)  or  gray  fibers  (Fig. 

194). 

519.  A    Neuron.  —  One    nerve   cell   to- 
gether with  all  its  branches,  both  dendrons  and  axon,  is 
called  a  neuron.     A  neuron  is  the  unit,  and  the  nervous 
system  is  built  up  of  an  enormous  number  of  these  units, 
together  with  supporting  tissue  (Fig.  193). 

520.  A  Nerve.  —  Many  nerve  fibers   may  be   bound  to- 
gether by  connective  tissue  until  they  form  a  cord  large 
enough  to  be  seen  by  the  unaided  eye  (Fig.  195).     A  bun- 
dle of  nerve  fibers  is  called  a  nerve.     The  sciatic  nerve  in 
the  thigh  is  as  large  as  the  end  of  the  little  finger  and  strong 
enough   to   support   the  weight  of  the   body.     The   fatty 
sheaths  of  the  fibers  are  supposed  to  insulate  the  fibers  so 
that  a  nerve  impulse  cannot  go  across  to  another  fiber;  they 
serve  the  same  purpose  as  the  insulating  substances  with 


FIG.  194. 

c,  medullated  or  white 
nerve  fiber;  rf,  two 
non-medullated  or 
gray  fibers. 


286  ELEMENTS  OF  PHYSIOLOGY 

which  wires  used  to  conduct  electricity  are  sometimes 
coated.  As  a  rule,  a  large  nerve  accompanies  an  artery 
down  the  inside  of  each  limb,  and  across  the  joint  on  the 
side  toward  which  the  limb  bends.  Thus  they  are  well 
protected.  One  exception  to  this  is  a 
nerve  cord  which  crosses  the  elbow  on 
the  side  away  from  which  the  elbow 
bends.  Therefore  it  is  sometimes  hit, 
and  the  end  of  the  bone  there  is  called 
the  funny  bone  because  of  the  tingling 
sometimes  felt,  as  if  it  were  in  the  hand 
at  the  termination  of  the  nerve. 

521.  A  Nerve  Ganglion  and  a  Nerve 
Center.  —  The  cells  are  not  scattered 
singly  throughout  the  nervous  system 
but  are  gathered  into  groups.  This 
seems  to  afford  easier  communication 
from  one  cell  to  another  through  their 
branched  dendrons,  which  are  unusually 

FlG.    195.  —  Section    of      .  _  r        ..     .          ,,     . 

Nerves,  showing  Many    short.       One  SUCh  group  of  Cells  IS  Called 

Nerve  Fibers  in  Con-  a    ganglion.      One    or    more    ganglia, 

nective  Tissue  Sheaths.          6r      6. 

performing  a  definite  function,  such  as 
controlling  the  muscles  of  breathing,  form  what  is  called  a 
nerve  center.  The  brain  consists  of  a  number  of  large  nerve 
centers  with  their  connecting  fibers.  There  are  many 
nerve  centers  in  the  spinal  cord  also.  We  usually  speak 
of  the  brain  and  spinal  cord  as  the  central  nervous  system. 
Where  ganglia  and  gray  fibers  are  abundant,  the  nerve 
substance  is  gray  ;  where  medullated  fibers  with  their  hid- 
den gray  cores  are  abundant,  the  nerve  substance  is  white 
in  appearance.  This  led  anatomists  and  physiologists  in 
times  past  to  classify  nerve  substance  as  gray  matter  and 
white  matter. 

522.  Neuroglia. — The  fibers  and  cells  of  both  the  gray 
and  the  white  matter  are  held  in  place  by  a  tissue  called 


THE  NERVOUS  SYSTEM  28? 

neuroglia,  which  is  composed  of  extremely  fine  fibers  and 
minute  cells.  Though  like  connective  tissue  in  function, 
its  chemical  composition  is  different,  nor  is  neuroglia  de- 
veloped from  connective  tissue  (Fig.  193). 

523.  How  Nerve  Fibers  terminate.  —  If  we  could  trace 
toward  the  central  nervous  system  the  course  of  the  various 
nerve  fibers  in  a  nerve  like  the  great  sciatic,  for  example, 
we  should  find  that  every  one  of  its  thousands  of  nerve 
fibers  ends,  without  exception,  in  a  nerve  cell  in  the  spinal 
cord  or  brain,  or  in  one  of  the  ganglia  near  the  central 
nervous  system.     If   we  should   trace    these  same  fibers 
away  from  the  central  nervous  system,  they  would  be  found 
to  have  various  endings.     Some  enter  the  muscles  where 
they  subdivide,  and  finally  end  in  the  muscle  cells.     Others 
follow  the  blood  vessels,  and  end  in  the  muscle  fibers  form- 
ing the  middle  layer  of  their  walls.     Others  go  to  the  gland 
cells  ;  for  example,  the  sweat  glands  in  the  skin,  or  to  some 
other  internal  gland.     Others,  passing  to  the  skin,  termi- 
nate at  the  roots  of  the  hair,  or  in  curious  little  bodies  com- 
posed   of   cells    and    called    touch    corpuscles   (Fig.    196). 
Every  nerve  fiber  ends  centrally  in  a  nerve  cell,  and  out- 
wardly in  either  a  muscle  cell,  gland  cell,  or  sense  organ  cell. 

524.  Motor  and  Sensory  Fibers. — Fibers  which  connect 
nerve  cells  with    muscles  or  glands  are  called  motor  or 
efferent  (outward   bearing),   fibers ;    those  which   connect 
nerve  cells  with  sense  organs  are  called  sensory  or  afferent 
(into  bearing)  fibers.     There  is  a  third  kind,  which  connects 
nerve  cell  with  nerve  cell  in  the  brain ;  they  are  known  as 
association  fibers  (Figs.  203,  207). 

525.  Nerve  Action. —  If  the  sensory  nerve  be  irritated  at 
its  outer  endings  in  the  cells  of  the  other  tissues  or  any- 
where in  its  course,  an  influence  will  travel  to  the  central 
nervous  system.     If  the  impulse  reaches  the  brain  before 
dying  out,  it  will  be  felt  as  a  sensation.     On  the  other  hand, 
the  brain  can  originate  impulses  which  travel  to  the  cells  of 


288 


ELEMENTS  OF  PHYSIOLOGY 


the  body  and  cause  them  to  act.  Transmitting  impulses 
is  the  whole  duty  of  nerves.  The  endings  of  the  nerves 
are  so  abundant  in  the  skin  just  beneath  the  epithelium, 
that  the  point  of  a  fine  needle  cannot  enter  without  causing 
pain.  They  are  more  numerous  there  than  in  any  other 
part  of  the  body.  Sensory  nerves  are  not  so  abundant  in 
the  muscles  and  internal  organs  as  in 
the  skin,  so  that  a  cut  gives  most  pain 
as  it  enters  the  skin  and  may  be  con- 
tinued into  deeper  parts  with  only 
slight  pain.  Motor  nerves  begin  at 
the  central  nerve  cells  and  end  in  the 
cells  of  the  body.  Motor  nerves  and 
motor  impulses  are  for  three  pur- 
poses :  for  controlling  motion,  secre- 
tion, and  growth. 

526.  Special  Sensations.  —  When 
something  outside  of  the  body  acts 
upon  the  nerves,  it  produces  a  feel- 
ing or  sensation  by  which  the  mind 
forms  ideas  of  the  surroundings  of 
the  body.  The  meanings  of  these 
feelings  must  be  learned  when  first 
stained  with  Chiorid  of  perceived,  and  they  are  mostly  learned 
in  childhood.  The  special  senses  are 
of  such  importance  that  all  except 
the  sense  of  touch  will  be  included 
in  a  separate  chapter. 
527.  General  Sensations.  —  The  cells  of  the  body  are 
constantly  sending  impulses  to  the  central  nervous  system, 
signifying  their  needs.  These  impulses  give  rise  to  feelings 
to  which  the  mind  assigns  no  definite  location  in  the  body ; 
hence  they  are  called  general  sensations.  Such  feelings  as 
hunger,  thirst,  fatigue,  and  sleepiness  belong  to  this  class. 
They  are  as  well  understood  by  a  baby  or  any  young 


FIG.  196.  —  Tactile  Cor- 
puscle within  a  Papilla 
of  the  Skin  of  the  Hand, 


Gold. 

n,  two  nerve  fibers  passing  to 
the  corpuscle ;  a,  a,  ramifica- 
tions of  the  axis  cylinders 
within  the  corpuscle. 


THE  NERVOUS  SYSTEM  289 

animal  as  by  a  man,  and  unlike  the  special  sensations,  the 
meaning  of  general  sensations  does  not  have  to  be  learned, 
as  the  memory  of  them  owing  to  inherited  habit  seems  to 
reside  in  the  nervous  system.  General  sensations  are 
sometimes  called  instincts. 

528.  Hunger  and  Thirst  —  Thirst  seems  to  be  located  in 
the  mouth,  yet  moistening  the  mouth  satisfies  it  for  a  short 
time  only.     On  the  other  hand,  if  water  is  introduced  into 
the  body  through  the  intestine  or  veins,  the  thirst  ceases, 
even  if  the  mouth  has  not  received  water.     Hunger  appears 
to  be  located  in  the  stomach,  yet  it  cannot  be  satisfied  by 
filling  the  stomach  if  the  food  is  innutritious  or  remains 
undigested.1 

529.  Touch. — The  four  special  senses  of  sight,  sound, 
smell,  and  taste  are  located  in  special  organs.     Touch  is 
located  in  all  parts  of  the  body.     When  an  object  touches 
the   skin,    an   impulse  is  taken   to  the  brain  (Figs.   196, 
197,  3).     There  it  gives  rise  to  a  sensation  of  touch,  tem- 
perature, pain,  or  weight.    Four  kinds  of  sensations  are  thus 
included  in  the  general  name   of   touch.     Touch   strictly 
gives   only   such   ideas  as  those  of  size,  shape,  location, 
smoothness,  hardness,  and  dampness.     The  ends  of  the 
fingers  can    distinguish  two  points  as  separate   points  if 
they  are  only  -^  of  an  inch  apart,  while  if  the  two  points 
are  applied  to  the  back,  they  feel  as  if  they  were  one  point 
until  they  are  separated  two  inches. 

530.  The  covering  of   epidermis  not  only  protects  the 
nerves  and  the  other  delicate  organs  in  the  true  skin,  from 
injury,  but  also  modifies  any  impression,  so  that  in  pro- 
ducing a  sensation  it  is  spread  over  several  nerve  endings 
instead  of  one,  and  is  thus  turned  into  a  gentle  instead  of 
a  painful  sensation  (Fig.  3). 

1  If  nutritious  food  is  introduced  into  the  body  through  the  intestine  in  a 
form  ready  to  be  absorbed,  the  feeling  of  hunger  will  soon  pass  away,  although 
the  stomach  is  still  empty. 

U 


290 


ELEMENTS   OF  PHYSIOLOGY 


531,  Temperature.  —  This  part  of  the  sense  of  touch  is 
located  only  in  certain  points  or  spots,  called  heat  spots 

and  cold  spots,  situated  a 
small  fraction  of  an  inch 
apart  (Fig.  198).  Some 
spots  give  a  sensation  of 
heat  only,  and  some  of 
cold  only.  The  sense  is 
so  delicate  that  a  differ- 
ence of  \  of  a  degree  of 

FIG.  197.  — Four  Papillae  of  the  True  Skin, 

magnified.     The   epidermis   has  been   re-    temperature  between  two 
moved.     Most  papillae  contain  touch  cor-    objects    Can  be  detected. 

Extremely  hot  and  cold 

objects  injure  the  tissues  and  do  not  give  sensations   of 
temperature,  but  only  of  pain. 

532.  Pain.  —  A     sensation 
greatly  increased  or  often  re- 
peated   becomes    unpleasant 
and  is  called  pain.     The  same 
physical    influence    may    be 
felt  at  one  time  as  a  pleasant 
touch,  and  at  another  time  as 
a  pain,  depending  upon  the 
state    of    the     nerve    tissue. 
When  an  influence  is  becom- 
ing strong  enough  to  endan- 
ger   the    body,    the     simple 
sensation   of   touch  becomes 
changed    into    one    of    pain 
and    warns   us   to   avoid   the 
danger.     When    a    nerve    is 
laid  bare  and  touched,  or  cut 
midway  in  its  course,  the  feel- 
ing is  not  one  of  touch,  but  of  pain.     Pain  is  a  protection, 
and   therefore   more  of  a  good  than  an  evil.      In    many 


FIG.  198.  —  Cutaneous  "Cold"  Spots 
(light  shading)  and  "Hot"  Spots 
(dark  shading)  ;  Anterior  Surface  of 
the  Thigh. 


THE  NERVOUS  SYSTEM  29 1 

diseases  it  is  a  prominent  symptom,  and  the  physician  is 
begged  to  give  relief.  But  the  wise  physician  hesitates  be- 
fore giving  morphine  or  other  sedatives,  knowing  that  to 
drown  the  pain  is  to  conceal  the  danger,  and  take  away  his 
best  evidence  as  to  the  state  of  the  disease.  At  the  same 
time,  he  runs  a  risk  of  starting  a  habit  in  the  patient  of 
deadening  pain  and  hiding  unpleasant  feelings  by  taking  nar- 
cotics, a  habit  that  may  become  fastened  upon  the  patient 
and  ruin  his  life.  Hence  when  sick  we  should  bear  pain 
bravely. 

533.  Tickling  is  intermediate  between  touch  and  pain. 
It  is  produced  in  parts  which  are  supplied  with  few  nerves 
of  touch,  as  under  the  arm.     It  may  produce  great  suffer- 
ing.    Some  persons  who  can  endure  great  pain  cannot 
control  themselves  when  tickled,  as  the  movements  excited 
are  largely  reflex.     Itching  is  a  sensation  akin  to  tickling. 
It  may  be  overcome  by  producing  a  greater  sensation,  as 
by  scratching.     Sometimes  it  may  be  so  great  as  to  lead 
a  person  to  injure  the  skin  seriously  by  deep  scratching. 

534.  The  Muscular  Sense.  — When  an  object  is  lifted,  it 
is  felt  to  be  distinctly  heavier  if  its  weight  is  increased  by 
only  Tay>  but  when  it  is  laid  upon  the  skin,  its  weight  must 
be  increased  by  \  before  it  feels  heavier.     Hence  it  is 
concluded  that  sensations  of  weight  and  resistance  to  the 
muscles  depend  upon  the  amount  of  muscular  effort  needed 
to  overcome  the  resistance  as  well  as  upon  the  feelings 
of  pressure  upon  the  skin  and  body. 

535.  If  Motor  or  Efferent  Nerves  going  to  a  muscle  are 
cut,  there  is  paralysis  of  the  muscle,  so  that  there  can  be  no 
voluntary  or  reflex  action  in  the  part.     If  an  efferent  nerve 
going  to  a  gland  is  cut,  the  function  of  the  gland  will  be  almost 
suspended.     Even  if  food  is  taken  into  the  mouth  and  the 
sensory  nerves  carry  the  news  to  the  brain,  the  efferent 
nerve  being  cut,  no  impulse  can  return  and  the  secretion 
will  be  very  slight.     When  the  motor  nerve  to  a  part  is 


ELEMENTS  OF  PHYSIOLOGY 

cut,  the  cells  will  be  almost  too  inactive  to  absorb  and 
carry  on  growth  and  repair;  hence  unless  continually 
under  the  influence  of  motor  nerves  the  cells  dwindle 
away.  When  the  cells  are  much  used,  the  impulses  sent 
cause  them  to  take  in  more  nourishment  and  grow  in  size. 
Thus  a  muscle  increases  in  size  and  strength  when  much 
used.  You  learned  that  during  the  action  of  a  muscle,  the 
vasomotor  nerves  going  to  the  arteries  in  the  muscle  cause 
what  change  ?  Will  this  also  aid  in  growth  ?  When  a 
nerve  is  cut,  the  ends,  if  placed  together,  will  grow  again, 
the  parts  supplied  by  it  being  paralyzed  in  the  meantime. 

536.  Disease  of  Nerves  and  Effect  of  Alcohol.  —  Nerves 
may  become  inflamed,  and  the  disease  is  called  neuritis, 
just  as  inflammation  of  the  tonsils  is  called  tonsilitis,  or  of 
the   stomach   is   called  gastritis.     Neuritis  of  the  sciatic 
nerve  is  called  sciatica ;  it  is  a  very  painful  disease.     One 
of  the  many  dangers  of  using  alcohol  is  that  it  may  pro- 
duce neuritis.     Either  slow,  steady  drinking  or  occasional 
sprees  may  cause  it.     The  disease  gives  no  warning  before 
it  comes,  and  may  remain  a  long  while.     Rheumatism  or 
malaria  may  also  cause  it,  but  alcohol  produces  the  disease 
as  often  as  all  other  causes  combined. 

537.  The  Rate  of  Transmission  of  the  nerve  impulse  in 
white  fibers  is  about  one  hundred  feet  per  second.     In  the 
gray  fibers  the  impulse  travels  much  slower,  probably  about 
twenty  feet  per  second. 

THE  SPINAL  CORD 

538.  The  various  white  nerve  fibers,  both  motor  and 
sensory,   of   the  entire  body  unite  and  form  forty-three 
pairs  of  larger  nerves ;  twelve  of  these  pairs,  called  cranial 
nervesy  go  to  the  brain,  and  thirty-one  pairs,  called  spinal 
nerves,  go  to  the  spinal  cord.     Each  one  of  the  sixty-two 
spinal  nerves  enters  the  spinal  cord  by  two  roots,  one  pos- 
terior and  one  anterior  (Fig.  199).     It  is  significant  that 


THE  NERVOUS  SYSTEM  293 

all  of  the  motor  and  sensory  fibers  of  a  spinal  nerve  sepa- 

rate from  each  other.     The  motor  fibers  enter  by  the  an- 

terior root,  and  the  sensory  nerves  by  the  posterior  root. 

The    sensory   fibers    do    not   really 

enter  the  cord  but  end  in  a  ganglion 

on  the  posterior  root,  and  the  gan- 

glion sends  dendrons  into  the  cord 

by  the  posterior  root.      The  spinal    FIG.  199.  —  Cross-section  of 

cord  extends  from  the  foramen  mag-      %^  «£  •££ 

"  Or  great  Opening,"  in  the  OCci-         and  Anterior  and  Posterior 


..-•1  i  ,  ,         Nerve  Roots.    Ganglion  on 

pital  bone  down  to  about  the  second       Posterior  Root. 
lumbar  vertebra.     What  parts  of  a 

vertebra  form  the  canal  for  the  cord  ?  Is  the  canal  made 
of  bone  throughout  its  length  ?  How  are  the  vertebrae 
united  with  one  another? 

539.  The  spinal  cord  is  about  the  size  of  the  little  finger. 
It  is  only  about  two  thirds  as  large  as  its  tube,  so  that  it  is  not 
likely  to  be  injured  by  bending  the  backbone.     The  rest  of 
the  space  in  the  canal  is  taken  up  by  a  lymphlike  liquid  and 
three  membranes  called  meninges,  which  form  a  triple  cov- 
ering for  the  cord.     These  membranes  extend  into  the  skull 
and  cover  the  brain.     An  inflammation  of  them  constitutes 
a  very  serious  disease  called  cerebro-spinal  meningitis. 

540.  A  Cross-section  of  the  spinal  cord  shows  that  it 
is  a  double  organ  (Fig.  199),  the  halves  being  united  by  a 
narrow  portion  ;  it  shows  also  that  the  central  part  of  the 
cord  is  of  gray  matter  in  the  outline  of  a  butterfly,  and  sur- 
rounded by  a  thick  layer  of  white  fibers.     The  gray  por- 
tion is  made  up  of  nerve  cells  that  give  off  fibers,  many  of 
which  go  to  the  spinal  nerves  and  some  go  upward  in  the 
outer  white  portion  of  the  cord.     The  white  tract  also  con- 
tains motor  threads,  bringing  impulses  from  the  brain  to 
the  cells  in  the  gray  matter. 

541.  Voluntary  Motion  and   Action  of  the  Spinal  Cells.  — 
The  brain  sends  impulses  to  the  cells  in  the  spinal  cord, 


294  ELEMENTS   OF  PHYSIOLOGY 

and  they,  being  aroused,  in  turn  send  motor  impulses  to 
the  muscles.  When  a  person  wills  to  move  his  hand,  an 
impulse  goes  to  the  spinal  cells,  and  they  in  turn  send  im- 
pulses that  cause  a  contraction  of  the  muscles  in  the  arm. 
The  brain  sends  about  ten  impulses  per  second  to  keep  the 
muscle  in  action.  Thus,  before  it  can  relax,  another  im- 
pulse reaches  it.  Each  muscle  has  its  own  set  of  spinal 
cells  in  the  cord  which  act  as  a  relay  station  between  the 
muscle  and  the  brain. 

542.  The  Spinal  Cord  and  Reflex  Action.  —  The  cells  of 
the   spinal  cord  have  another  very  important  duty  ;  they 
largely  control  reflex  action.     At  times  it  would  take  too 
long  for  the  brain  to  act,  so  the  body  needs  a  quicker 
governing   power  to  supply  its  needs  or  protect   it  from 
injury.     If  the  finger  touches  a  hot  object,  the  brain  be- 
comes conscious  of  the  burn  and  of  the  movement  of  the 
finger  at  about  the  same  time.     There  are  also  many  acts 
that  are  performed  so  often  that  the  spinal  cord  acquires 
the  habit  of  sending  back  the  appropriate  impulses.     Thus 
muscles  and  other  organs  may  be  controlled  and  the  brain 
be  relieved  to  attend  to  other  duties. 

543.  The  same  motor  cells  of  the  spinal  cord  that  pro- 
duce motion  in  a  part,  also  exercise  an  oversight  that  con- 
trols the  growth  and  nutrition  of   the  cells  in  that  part. 
The   impulses   from   the  spinal   cells   furnish  a   constant 
stimulus  to  growth  and  repair. 

544.  Examples  of  Reflex  Action.  —  A  crumb  entering  the 
larynx  brings  on  a  fit  of  coughing.     A  dash  of  cold  water 
makes  us  hold  our  breath.     A  pinch  of  snuff  or  pepper 
causes  us  to  sneeze.     If  the  foot  of  a  sleeping  person  is 
tickled,  he  will  kick  ;  if  a  fly  settles  on  his  face,  he  will 
brush  it  off.     Sometimes  a  person  in  an  unconscious  con- 
dition will  drink  a  cup  of  water  if  it  is  placed  to  the  lips. 

545.  If  the  back  is  broken,  reflex  actions  persist  although 
all  sensation  and  volition  concerning  the  parts  below  the 


THE  NERVOUS  SYSTEM  2Q5 

injury  are  suspended.  The  leg  will  kick  when  the  foot  is 
tickled,  etc.  A  surgeon  tickled  the  foot  of  a  man  whose 
spinal  cord  was  injured,  and  the  feet  kept  up  a  vigorous 
kicking.  He  asked  the  man  if  he  felt  it ;  he  said,  "  No, 
but  you  see  that  my  feet  do."  On  carefully  testing  the 
sensibility  of  such  a  man,  a  line  can  be  traced  girdling  the 
body,  dividing  the  sensitive  from  the  insensitive  part.  The 
brain  also  may  act  seemingly  in  a  reflex  manner  as  in 
cases  of  somnambulism,  or  sleep-walking. 

546.  When  one  is  learning   new   movements,    such   as 
walking,  skating,  writing,  riding  a  bicycle,  each  movement 
is  a  voluntary  one  as  far  as  the  will  is  capable  of  watching 
so  many   muscles.     The  movements  are,  therefore,  slow 
and   awkward.     After   the   movements    have   been  made 
many  hundreds  of  times,  they  becomes  easy  and  graceful, 
and  also  less  voluntary.     Finally,  one  may  learn  to  walk, 
cycle,  or  play  the  piano  with  the  attention  fixed  on  some- 
thing else.      Such  movements   are    called  "  acquired    re- 
flexes."    There  is  evidence  to  show  that  the  axons  become 
covered  with  a  medullated  coat,  as  each  new  pathway  and 
tract  is  beaten  through  the  nervous  system  by  repeated  ex- 
periences.   Thus  the  structure,  like  the  habit,  becomes  fixed. 

547.  Reflex  Action  and  Education.  —  Education  of  reflex 
action  consists  mainly  of  the  formation  of  habits.     The  im- 
pression on  the  nervous  system  from  the  training  is  made 
chiefly  on  the  spinal  centers.     When  the  muscles  of  the 
hand  are  educated,  it   is   really  the  spinal  cells  that  are 
educated.     During  youth,  one    is    always  acquiring  good 
habits  or  bad  habits.     The  habit  of  an  upright,  easy  walk, 
the  habit  of  dropping  into  a  stooping  posture,  of  putting 
the  hands  in  the  pockets,  of  making  wry  faces,  of  mum- 
bling and  stammering,  or  of  talking  distinctly  and  without 
hesitation,   may   be   acquired,   and   will    probably   remain 
ihrough  life,  tor  impressions  made  on  the  nervous  system 
in  youth  are  lasting.     The  habit  of  Beating  temperately  of 


2Q6  ELEMENTS   OF  PHYSIOLOGY 

pure  food,  the  habit  of  stuffing,  of  awaking  the  nerves  with 
stimulating  condiments,  of  using  alcoholic  stimulants,  of 
using  tobacco,  are  easily  acquired,  but  are  lost  with 
difficulty.  Good  habits  are  good  friends;  bad  habits  are 
enemies.  It  often  requires  years  of  constant  effort  to  root 
out  bad  habits,  but  it  is  very  easy  to  keep  them  out  in  the 
first  place.  Yet  if  the  wish  and  will  for  a  better  habit  is 
really  strong,  one  need  never  despair,  for  on  account  of  the 
large  size  and  great  activity  of  the  brain,  and  its  prepon- 
derance over  the  lower  reflex  centers,  man  is  distinguished 
above  all  other  animals  by  his  power  of  forming  new  habits. 
If  our  ideals  are  high,  we  can  go  on  forming  better  habits, 
and  intrusting  them  to  the  keeping  of  the  nerve  centers,  and 
thus  make  step  after  step  toward  our  ideal.  If  our  ideals 
are  not  high,  or  if  they  are  mere  theories  and  never  affect 
our  acts,  we  may  never  improve,  but  may  even  degenerate. 
The  brain  and  the  spinal  cord  with  the  nerves  that  branch 
from  them  form  the  cerebro-spinal  system. 

THE  SYMPATHETIC,  OR  GANGLIONIC,  SYSTEM 

548.  This  System  consists  of  numerous  ganglia  situated 
apart  from  the  brain  and  spinal  cord,  and  many  gray  nerve 
fibers  which  connect  these  ganglia  with  the  spinal  cord, 
with  each  other,  and  with  the  cells  controlled  through  this 
system.    (What  is  lacking  in  the  gray  fibers  that  is  present 
in  white  fibers  ?)     The  sympathetic  nervous  system  con- 
trols the  functions  of  unconscious  life,  while  the  brain  and 
spinal  cord  control  the  functions  of  conscious  life. 

549.  The  chief  functions  controlled  through  the  sympa- 
thetic system  are  the  peristalsis  of  the  intestine,  the  growth 
of  cells,  and  the  contraction  of  the  heart,  arteries,  and  veins. 
The  nerves  that  go  to  the  arteries  and  veins  are  named 
the  vasomotor  nerves.      The  ganglia  of  the  system  vary 
in  size  from  minute  specks  to  the  size  of  a  grain  of  wheat, 
a  pea,  or  a  bean.     There  is  a  double  row  of  the  large  ones 


THE  NERVOUS  SYSTEM 


297 


that  runs  down  in  front  of  the  backbone,  all  connected  by 
nerves.  The  nerves  of  the  system  form  several  intricate 
networks,  each 'called  a  plexus 
(Fig.  200).  The  largest  and 
most  important  is  the  solar 
plexus,  just  behind  the  stom- 
ach; its  nerves  supply  the 
muscular  walls  of  the  abdomi- 
nal organs.  Another  plexus  is 
found  in  connection  with  the 
heart. 

550.  Sensory  Nerves  of  the 
Sympathetic     System.  -  -  The 
sensory  impulses  through  these 
nerves  are  slow  and  faint,  sel- 
dom reaching  beyond  the  spinal 
ganglia   to   the   brain.      Thus 
the   circulation    of    the   blood 
and  the  digestion  of  the  food 
usually  go  on  without  our  con- 
sciousness, but   a  very  strong 
irritation  may  give  rise  to  con- 
sciousness   and    pain    in    the 
abdominal  organs,  as  in  colic 
or  in  vomiting.      Sensory  im- 
pulses, signifying  the  needs  of 

the  cells  and  the  necessitv  for    FIG.  200.  -  Diagram  of  Trunk  show- 
in?  One  of  the  Two  Rows  of  Svmoa- 

movement  in  the  arteries  and 
intestines,  are  being  continu- 
ally sent  to  the  spinal  ganglia. 
Only  very  strong  impulses 
caused  by  disturbances  that  may  injure  the  body,  reach 
the  brain,  and  cause  pain. 

551.  Motor    Sympathetic   Nerves.  —  The   motor   nerves 
carry  impulses  which   cause   the   epithelial   cells   of   the 


ing  One  of  the  Two  Rows  of  Sympa- 
thetic Ganglia  near  the  Spinal 
Column  and  the  Plexuses. 

i,  cardiac  plexus;  2,  solar  plexus;  3,  hy- 
pogastric  plexus;  4,  5,  6,  7,  row  of 
ganglia  near  spinal  column. 


298  ELEMENTS   OF  PHYSIOLOGY 

glands  to  make  their  secretions,  and  the  muscles  of  the 
arteries  and  intestines  to  contract.  They  do  this  as  a 
reflex  response  to  the  impulses  going  to  the  spinal  ganglia 
from  the  sensory  nerves  of  the  system.  The  pressure  of 
food  in  the  stomach  excites  the  flow  of  the  secretions.  At 
a  flash  of  bright  light  the  eye  winks  and  the  pupil  con- 
tracts. The  sweat  glands  secrete  under  the  influence  of 
warmth.  It  was  formerly  believed  by  physiologists  that 
the  sympathetic  ganglia  themselves  sent  the  reflex  motor 
impulses,  but  it  is  now  believed  that  these  come  from  the 
spinal  ganglia.  The  sympathetic  ganglia  are  supposed  to 
reenforce  the  current  and  aid  in  the  nutrition  of  the  nerves 
that  pass  through  them. 

552.  The  Brain    has    Considerable   Influence    over    the 
sympathetic   nerves,   but   in   an  indirect   way.     We   can- 
not control  the  digestion  or  the  heart  beat  by  the  will,  yet 
the  thoughts  and  emotions   may  powerfully  affect  them. 
The  face  blushes  from  dilatation  of  its  blood  vessels  when 
one  is  embarrassed  or  self-conscious.      It  becomes  pallid 
with   fear.     Sorrow   depresses   the   activity  of  the   cord, 
which  in  turn  sends  out  fewer  orders,  so  that  the  food  is 
not  digested  and  the  cells  are  not   nourished.      Yet   to 
guard  against  too  great  interference  by  the  emotions  and 
the  mind,  nature  has  arranged  that  impulses  starting  at 
the  brain  must  pass  through  at  least  two  sets  of  ganglia 
before   they  can   affect   nutrition    and   circulation.      The 
examination  of  the  food  is  carried  on  by  the  higher  senses 
and  the  brain,  for  it  is  important  that   hard  things  and 
poisonous  substances  should  not  be  swallowed.     But  the 
regulation  of  the  flow  of  the  saliva  is  left  to  the  gray 
matter  at  the  top  of  the  spinal  cord  ;  the  secretion  of  the 
saliva  is  a  reflex  act  excited  by  the  taste  of  the  food,  and 
does  not  enter  into  consciousness. 

553.  Strong  influences  are  needed  to  impair  the  action 
of  the  sympathetic   nerves   and  ganglia.      Poisons  which 


THE  NERVOUS  SYSTEM  299 

are  swallowed  or  produced  in  the  body  by  disease,  may 
excite  them  to  vigorous  action  and  cause  vomiting,  or  may 
injure  them  so  that  their  impulses  almost  cease.  Aside 
from  this,  about  the  only  danger  to  which  the  system  is 
exposed  is  a  blow  upon  the  abdomen  or  neck ;  such  a  blow 
is  always  dangerous.  Death  may  then  result  through  shock 
to  the  heart,  or  through  paralysis  of  the  vasomotor  nerves, 
which  causes  the  arteries  to  enlarge  and  hold  so  much 
blood  that  too  little  goes  to  the  brain.  "  Fidgets  "  is  caused 
by  poisons  from  fermented  food  going  to  the  sympathetic 
ganglia  and  irritating  them.  Backache  in  women  is  some- 
times caused  by  the  abdominal  organs  being  prolapsed  or 
pushed  downward  by  the  pressure  of  a  tight  corset,  or  pulled 
down  by  the  weight  of  skirts  supported  by  these  organs. 
This  causes  the  sympathetic  nerves  to  be  stretched  at  their 
attachment  near  the  spine. 

554.  Sympathy  in  functional  activity  between  the  va- 
rious vital  organs  is  brought  about  through  this  system,  and 
gives  it  its  name.     Derangement  of  the  stomach  may  affect 
the  heart.     One  organ  seems  to  share  in  the  illness  when 
another  is  deranged.     This  is  well,  for  when  one  organ  is 
diseased,  the  others  do  not  continue  to  act  and  impose  work 
upon  the  ailing  organ.     A  feeling  of  weakness,  which  rests 
the  muscles,  and  a  loss  of  appetite,  which  rests  the  digestive 
organs,  accompany  most  forms  of  illness. 

555.  THOUGHT  LESSON.     Obedience  to  Natural  Law.  — 

1.  What  is  the  natural  direction  of  growth  of  the  big 
toe? 

2.  Think  of  six  evil  results,  direct  or  indirect,  which  will 
follow  the   transgression  of  God's  design  in  this   simple 
matter. 

3.  Which  part  of  the  spinal  column,  designed  in  infinite 
wisdom  to  be  most  flexible,  do  some  people  try  to  make  the 
most  inflexible  ? 

4.  The  mobility  of  the  false  and  floating  ribs  was  intended 


3OO  ELEMENTS   OF  PHYSIOLOGY 

as  a  blessing.     Some  people  interpret  the  blessing  as  an 
opportunity  to  do  what? 

5.  Name  six  articles  which  God  has  warned  us  are  in- 
jurious by  giving  them  bitter,  burning,  or  nauseating  tastes, 
yet  which  are  used  by  man. 

6.  Name  six  feelings  which  are  intended  as  warnings 
for  our  guidance,  but  which  are  commonly  disregarded. 

THE  BRAIN 

556.  The  spinal  cord  can  act  only  in  response  to  im- 
pulses at  the  moment  they  are  received.     The  brain  can 
originate  impulses  which  are  not  in  direct  response  to  a 
stimulus  from  the  outer  world.     Its  acts  are  apparently 
spontaneous,  but  they  probably  result  from  the  combina- 
tion of  impulses  previously  received,  which  memory  has  en- 
abled it  to  store  up  and  retain.     The  brain  not  only  causes 
action  and  directs  the  cord  in  giving  order  to  voluntary 
movements,  but  it  can  restrain  excessive  action  in  the  spinal 
cord.     Self-control  comes  largely  through  the  power  pos- 
sessed by  the  brain  of  restraining  the  spinal  cells  from 
sending  out  reflex  impulses  when  strong  and  sudden  im- 
pulses are  received  from  the  outer  world.     This  is  called 
the  inhibitory  power.      If  a  door  slams,  a  person  whose 
brain  is  not  exerting  good  control  jumps  suddenly. 

557.  The  Coverings  of  the  Brain.  —  What  facts  did  you 
learn  about  the  skull,  showing  that  it  is  well  constructed 
for  protecting  the  brain  ?     The  brain  is  covered  by  three 
membranes ;  the  outer  tough  one  lines  the  skull  and  the 
spinal  canal.     The  next  is  thinner.     There  is  a  lymphlike 
fluid,  called  the  cerebro-spinal  fluid,  within  this  membrane, 
so  that  the  brain  is  surrounded  by  a  kind  of  water  bed. 
The  third,  and  innermost  covering,  is  hardly  a  membrane, 
for  it  is  merely  a  thin  network  of  fine  blood  vessels  and 
connective  tissue.     It  dips  down  into  every  depression  and 


THE  NERVOUS  SYSTEM  301 

fold  of  the  outer  layer  of  gray  cells  of  the  brain, 
carrying  its  supply  of  blood.  This  layer  is  called  the 
cortex.  The  folds  are  called  Convolutions  (see  Plate 
VII). 

558,  The  Weight  of  the  Brain  of  the  average  man  is  forty- 
nine  ounces  (a  little  over  three  pounds),  and  of  the  average 
woman  is  forty-four  ounces.    The  woman's  brain  is  as  large 
in   proportion   to  the  size  of   her  body  as   man's  brain. 
Man's  brain  is  surpassed  in  weight  by  the  brains  of  only 
two  animals.     A  whale,  measuring  seventy  feet  long,  has 
a  brain  weighing  only  five  pounds,  and  an  elephant's  enor- 
mous body  is  controlled  by  a  brain  of  about  eight  pounds. 
Birds'  brains  are  heavier  in  proportion  to  their  bodies  than 
the  brain  of  any  other  animal.     The  brain  grows  very 
rapidly  till  the  fifth  year,  then  very  slowly;  the  growth 
after  twenty  is  very  slight.      Cromwell's  brain  is  said  to 
have  weighed  almost  eighty  ounces.      Other  great  men 
have  had  large  brains,  but  some  great  minds  have  inhab- 
ited very  small  brains.     Quality  is  as  important  as  quantity. 
The  brains  of  idiots  are  usually  very  small. 

559.  The  Parts  of  the  Brain  are  the  cerebrum,  cerebellum 
and  cerebral  ganglia.      The  cerebrum,  or  great  brain,  is 
highest  in  the  skull,  and  covers  all  the  other  parts ;  man 
is   the  only   animal   of    which   this   is   true   (Plate    VI). 
Sense-perception,  consciousness,  reason,  and  the  will  are 
located  in  the  cerebrum. 

The  cerebellum,  or  small  brain,  is  at  the  base  of  the 
skull  behind.  If  a  pigeon  has  its  cerebellum  removed, 
it  is  restless  and  has  wide-open  eyes ;  it  flutters,  but  can- 
not fly.  If  the  cerebrum  is  removed,  leaving  the  cere- 
bellum, it  is  stupid,  but  flies  if  thrown  into  the  air.  By 
placing  the  hand  at  the  back  of  the  skull  between  the 
occiput  and  the  neck,  you  will  cover  the  part  occupied  by 
the  cerebellum.  Coordination  of  the  muscles  is  believed 
to  be  carried  out  by  the  cerebellum.  You  will  to  walk 


302  ELEMENTS   OF  PHYSIOLOGY 

through  activity  of  the  cerebrum;  the  control  of  the 
muscles  while  walking  is  the  function  of  the  cerebellum. 

The  cerebrum  and  cerebellum,  like  the  spinal  cord,  are 
divided  by  deep  clefts  into  hemispheres.  The  cerebral 
ganglia  are  in  the  lower  central  region  of  the  cavity  (see 
Plate  VII). 

560,  The  Medulla  Oblongata.  —  This,  the  most  important 
of  the  cerebral  ganglia,  is  sometimes  called  the  spinal 
bulb.  It  may  be  looked  upon  as  the  part  of  the  spinal 
cord  within  the  skull.  It  is  just  within  the  foramen  mag- 
num, and  is  intermediate  in  position  and  function  between 
the  brain  and  spinal  cord.  The  spinal  cord  acts  reflexly ; 
the  brain  acts  consciously.  Conscious  actions  are  those 
which  are  influenced  by  mental  images  or  ideas.  The 
medulla  contains  reflex  centers  and  the  centers  of  auto- 
matic action.  This  kind  of  action  should  not  be  confused 
with  acquired  reflexes,  such  as  walking,  to  which  the  term 
automatic  is  sometimes  applied.  Automatic  centers  are 
those  which  are  controlled  by  the  condition  of  the  blood. 
They  are  stimulated  by  an  increase  of  carbon  dioxid  in 
the  blood.  The  chief  of  these  centers  is  the  respiratory 
center  of  the  medulla.  If  it  is  injured,  death  ensues  by 
suffocation.  It  is  sometimes  called  the  vital  knot,  because, 
although  the  cerebellum  or  even  the  cerebrum  may  be 
injured  or  removed  from  the  lower  animals  without  causing 
death,  the  smallest  injury  to  the  respiratory  center  kills 
the  animal  immediately.  In  cases  of  hanging,  it  is  injury 
to  this  center  that  causes  death.  Another  very  important 
center  in  the  medulla,  controlled  by  automatic  action,  that 
is,  by  the  varying  condition  of  the  blood,  is  the  center  for 
vasomotor  nerves,  which  regulate  the  size  of  the  blood 
vessels.  It  was  previously  learned  that  the  vasomotor 
fibers  belong  to  the  sympathetic  system.  There  are  also 
important  reflex  centers  in  the  medulla,  viz.,  the  centers 
for  the  secretion  of  saliva,  for  swallowing,  for  vomiting. 


THE  NERVOUS  SYSTEM 


303 


561.  How  Automatic  Centers  work.  —  As  the  blood  be- 
comes deficient  in  oxygen  and  charged  with  carbon  dioxid, 
the  respiratory  center  is  irritated  and  sends  out  im- 
pulses which  cause  deeper  breathing.  This  improves  the 
condition  of  the  blood,  and  the  respiration  is  quieter  until 
the  blood  again  loses  oxygen;  then  stronger  impulses  are 


Face  Sensory -j — 

Face  Motion 

Taste 


-  Spinal  Cord 
1st  Spinal  Nerve 
2d  Spinal  Nerve 


FIG.  201.  —  Diagram  of  the  Twelve  Cranial  Nerves. 

There  are  twelve  pairs  of  cranial  nerves  which  arise  from  the  brain  and  go  out  through  holes 
in  the  lower  wall  of  the  skull.  (How  many  pairs  of  spinal  nerves  are  there  ?  )  The  cranial 
nerves  are  numbered,  according  to  the  location  of  their  roots,  from  above  downward. 

sent,  and  so  on,  thus  regulating  the  condition  of  the  blood 
automatically.  The  size  of  the  blood  vessels  is  regulated 
in  the  same  way  by  the  vasomotor  center  in  the  medulla, 
increase  of  carbon  dioxid  causing  contraction  of  the  sur- 
face vessels,  decrease  of  it  causing  relaxation.  Automatic 
acts  take  place  in  series.  Reflex  acts,  as  for  example, 


304 


ELEMENTS   OF  PHYSIOLOGY 


walking,  can  take  place  in  series  also,  but  the  first  stimulus 
in  reflex  acts  comes  from  without  the  body ;  in  automatic 
acts  from  the  blood. 

FUNCTIONS  OF  THE  CEREBRUM 

562.    "  There  was  once  a  man  who,  holding  out  a  piece 
of  his  own  skull,  begged  for  money  in  the  streets  of  Paris. 

The  upper  portion  of  the  vault 
of  his  skull  had  been  torn  off  by 
an  accident,  and  his  brain  was 
protected  only  by  the  strong 
fibrous  covering  of  the  dura  ma- 
ter. The  wound  otherwise  was 
healed,  and  the  man  strong  and 
well.  Now  for  a  small  sum  the 
beggar  would  allow  any  one  to 
press  upon  his  brain,  and  when 
this  was  done  he  lost  conscious- 
ness, and,  as  it  were,  fell  into  a 
deep  sleep.  But  when  the  pres- 
sure was  withdrawn,  conscious- 
ness returned,  and  the  man 
awoke.  So  soon  as  the  blood 
was  squeezed  out  of  the  cerebral 
hemispheres,  these  organs  ceased 
to  work  and  consciousness  van- 
ished "  (Hill).  If  the  blood 
vessels  of  the  neck  are  com- 

FIG.  202. -A  Sketch  to  show  how     pressed  SQ  as  to  cut  off  the  Qxy. 

One  Set  of  Nerves  takes  Messages     • 

gen  from  the  brain,  a  person 
becomes  unconscious.  If  the 
heart  suddenly  weakens  its  ac- 
tion very  much,  or  if  the  vaso- 
motor  nerves  allow  the  arteries  to  lose  tone  suddenly  and 
increase  their  capacity  for  blood,  the  person  faints,  from  a 


to  Certain  Centers  in  the  Brain, 
and  how  Another  Set  of  Nerves 
carries  Orders  from  these  Brain 
Centers  to  the  Mouth,  the  Hand, 
etc. 


THE  NERVOUS  SYSTEM  305 

weakening  of  the  circulation  through  the  brain.  Recovery 
is  brought  about  by  placing  the  head  on  a  lower  level  than 
the  body,  so  that  the  blood  may  run  to  the  brain  with  less 
exertion  on  the  part  of  the  heart.  A  violent  blow  on  the 
head  may  make  one  insensible  at  once.  By  breathing  chlo- 
roform, ether,  or  carbon  dioxid,  by  taking  morphine,  the 
quality  of  the  blood  may  be  so  altered  as  to  bring  sleep.  In 
order  that  the  brain  may  act,  it  must  be  con- 
stantly aroused  by  impulses  from  the  outer 
world.  There  is  a  case  reported  of  a  man 
all  of  whose  sensory  nerves  had  lost  sen- 
sibility except  in  one  eye  and  one  ear.  He 
fell  asleep  immediately  if  the  .  remaining 
sense  organs  were  closed.  The  conclusion 
to  be  drawn  from  the  foregoing  facts  is, 
that  a  man  loses  consciousness  so  soon  as 
his  cerebral  hemispheres  cease  to  act  ;  but 

his  heart  and  lungs  keep  at  work.     It  is  _ 

FIG.  203.  —  Micro- 

curious  that    touching    the   cerebrum,    or      scopic  Diagram  of 
stimulating  it  with  electricity,  when  it  has      cJ^^J^Jj 
been  exposed  by  accident,  arouses  no  sen-      Brain. 
sation,  although  this  organ  is  believed  to  A,  external  layer  of  as- 

.  .  .  .  ,_,.    .       ..  .  sociation  cells,  axons, 

be  the  seat  of  consciousness.     This  fact  is      anddendrons;  B,  Py- 


of  great  interest,  for  it  shows  that  impres- 

sions  coming  from  the  sense  organs  alone      the  layfir  of  medul- 

lated   fibers  C.    The 

enter  into  consciousness.  dendrons  of  the  Py- 

563.     Effect  of   removing  Cerebrum.  —     la™^"11 
After  destruction  of  the  cerebrum,  an  ani- 
mal may  continue  to  live  if  fed  by  hand.     It  can  run  about, 
and  swallow  food  placed  within  its  mouth.     It  will  be  dis- 
turbed by  a  loud  sound,  such  as  the  blowing  of  a  horn. 
It  might  avoid  a  bright  flame  if  placed  in  its  path,  but  would 
go  stupidly  against  other  objects  ;  but  it  is  idiotic,  for  all 
acts  of  intelligence  cease.     Its  time  is  spent  in  sleep  or 
mechanical  wandering.      A  frog  having  its  cerebrum  re- 


306 


ELEMENTS   OF  PHYSIOLOGY 


C.  Motor.    By 
which  we  move 


B.  Sensory.    By 
which  we  feel. 


little  Brain  or 
Cerebellum. 


FIG.  204.  —  The  Area  A  has  not 
been  as  definitely  located  as  the 
Areas  B  and  C. 

its  back,  swims  when 
thrown  into  water,  and 
when  placed  on  a  board 
that  is  slowly  tilted,  it 
will  preserve  its  balance 
by  climbing  to  the  top. 
These  actions  are  reflex 


Marrow 
edulla. 


A.  Intellectual.      rnr»ir^r1 
By  which  we  think   "lOVea 

some  more  ex- 
tensive powers 
than  a  warm- 
blooded ani- 
mal. It  starts 
to  hopping 
when  touched, 
avoids  obsta- 
cles in  its  path, 
recovers  its 
usual  position 
when  placed  on 


FIG.  206. — View  of  One  Cerebral  Hemisphere  from 
between  the  .Hemispheres,  showing  Motor  and 
Sensory  Centres. 


FIG.  205.  —  Motor  and  Sensory 
Centers.  Most  Centers  occur 
in  Both  Hemispheres,  and  if 
One  is  injured,  the  Other  will 
continue  to  work. 

but  of  a  higher  or- 
der than  a  simple  re- 
flex act.  The  reason 
the  frog  continues 
hopping  after  being 


THE  NERVOUS  SYSTEM  307 

touched  is  that  each  hop,  owing  to  the  contact  of  the  skin 
with  the  ground,  excites  another  hop ;  the  animal  never 
begins  to  move  of  its  own  accord. 

564.  Function  of  the  Cerebellum.  —  The  removal  of  the 
whole  of  the  cerebellum  from  an  animal  does  not  produce 
death  so  long  as  the  medulla  is  not  injured,  but  the  animal 
becomes   weak   and   unsteady  in  its    movements.     If  the 
cerebrum  remains,  the  mental  faculties  are  retained.     Dis- 
ease of  the  cerebellum  in  man  produces  dizziness  and  leads 
to  a  staggering,  reeling  gate.     Hence  it  is  believed  that 
the  function  of  the  cerebellum  is  to  aid  the  cerebrum  in 
the   control  of  the  muscles.     It  brings  about  proper  co- 
ordination of  the  muscular  movements,    so  that  in  such 
movements  as   standing,    walking,    talking,   the   different 
muscles  may  each  act  at  the  right  moment  and  with  due 
force.     The  spinal  cord  also  coordinates  movements.     For 
instance,  if  a  frog  is  decapitated  and  left  quiet  for  an  hour 
or  two,  so  that  the  spinal  cord  may  recover  from  the  shock 
due  to  the  injury,  it  may  be  made  to  execute  'seemingly 
purposeful  movements.     If  a  drop  of  acid  be  placed  on  the 
flank  of  such  a  frog,  the>leg  will  be  drawn  up  and  the  acid 
wiped  off  with    the   toes.      But   such  coordinated  move- 
ments are  not  accompanied  by  consciousness. 

565.  The  Motor  Area  in  the  Brain  (Figs.  204,  205,  206). 
—  A  wounded  soldier  was  brought  to  the  surgeons  of  the 
German  army  with  part  of  his  skull  torn  away.     The  sur- 
geons used  an  electric  current  to  test  whether  the  nerves 
were  paralyzed.     They  were  astonished  by  finding  that 
whenever  the  electric  current  was  applied  to  the  wounded 
part  of  the  head,  muscular  movements  were  excited.     It 
was  soon  determined  that  by  stimulating  electrically  a  cer- 
tain area  of  the  cerebral  cortex  movements  on  the  opposite 
side,  of  the  body  can  be  excited.     This  area  lies  under  the 
parietal  bone,  and  extends  from  the  top  of  the  brain  to 
the  level  of  the  ear.     By  experiments  on  monkeys  and 


308 


ELEMENTS   OF  PHYSIOLOGY 


dogs,  and  by  studying  cases  of  accidents  to  the  skull  in 
human  beings,  this  area  has  been  subdivided.  Stimulation 
of  the  lowest  part  causes  movements  of  the  face ;  of  the 
middle  part,  the  arm ;  and  of  the  upper  part,  the  leg,  the 


FiG.  207.  —  Diagram  of  the  Motor  Area  and  the  Motor  Tract  in  the  Brain. 

Find  centers  for  leg,  arm,  face.  Notice  that  most  of  the  motor  fibers  from  one  hemisphere 
cross  to  the  opposite  side  of  the  spinal  cord;  and  if  one  half  of  the  brain  is  injured  the 
opposite  half  of  the  body  loses  motion  and  sensation  (paralysis). 

Trace  nerve  impulse  from  cell  in  cortex  at  i  to  muscle  at  7. 

Trace  reflex  impulse  from  skin  at  «  to  muscle  at  7. 

movement  always  being  on  the  side  opposite  to  the  stimu- 
lation.    When  the  lowest  part  of  the  area  on  the  left  side 


THE  NERVOUS  SYSTEM  309 

in  right-handed  persons  is  injured,  the  power  of  speech  is 
lost.  The  comprehension  of  words  and  the  ability  to  write, 
read,  and  hear  language  is  not  lost.  With  left-handed  per- 
sons, this  center  is  on  the  right  side. 

566.  Other  Centers  in  the  Cerebrum  (Figs.  205,  206).- 
When  the  part  of  the  cerebrum  that  lies  behind  the  ear  is 
destroyed,  a  loss  of  the  memory 

for  the  meaning  of  words  may 
result.  One  can  speak,  but  his 

words  follow  each  other  without      .^.^^Auw^^gu          A 
sense  or  meaning.     The  sense  of      "  •&*=* 

hearing  is  supposed  to  be  located 
in  the  same  region.  The  sense  of 
sight  is  located  in  the  rear  part  of 
the  cerebrum.  If  the  rear  part 
of  the  left  hemisphere  is  de- 
stroyed, a  man  is  unable  to  see 
anything  to  the  right  of  his  nose 

when  his  eyes  are  directed  straight  FlG-  208.— The  Olfactory  Nerve, 
forward.  The  sense  of  smell  lies  The  main  nerve  ends  in  the  form  of  a 

bulb  on  the  floor  of  the  skull.     The 

at  the  base  of  the  cerebrum  toward     fibers  branch  from  this  buib  like  the 

,1        r          4.  /T7'          ,^/c\  roots  from  an  onion  and  spread  out 

the  tront  (1<  ig.  206).  on  the  walls  of  the  nasal  chamber. 

HYGIENE  OF  THE  NERVOUS   SYSTEM 

567.  Sleep. — The    cells    of    the    body    with    all    their 
industry   are   not   tireless,    and   at   intervals  require  rest 
(Fig.  210).      During  sleep  the  heart  beats  more  slowly, 
respiration  is   less  rapid,  the  muscles  in  general  are  re- 
laxed, the  gland  cells  diminish  their  secretions,  and  diges- 
tion is  slow.     The  production  of  heat  is  lessened  and  the 
body  must  be  protected  from  cold.     Yet  consciousness  is 
the  only  function  entirely  in  abeyance.     The  sound  of  a 
passing  vehicle  quickens  the  pulse  of   the  sleeper  with- 
out  awaking   him;    if  he  is  touched,    he   moves.      Sleep 
is  deepest  during  the  second  hour,  and  it  then  takes  a 


310  ELEMENTS   OF  PHYSIOLOGY 

much  louder  sound  to  awaken  him  than  during  later  hours. 
Sleep  becomes  gradually  lighter  until  awakening  occurs. 
When  consciousness  is  partly  awake,  the  condition  is 
called  dreaming.  In  somnambulism,  the  sleeper  may  talk 
or  walk  as  he  dreams. 

568.  For  a  sound  nervous  system,  nothing  is  so  indis- 
pensable as  plenty  of  sound  sleep.  It  is  necessary  .for 
growth  and  repair  of  the  cells  (Fig.  210).  Infants  sleep 
almost  all  the  time ;  children  of  four  or  five,  nearly  half  the 
time ;  those  of  ten  or  twelve,  ten  hours ;  most  college 


FIG.  209. 

A,  auditory  center;  B,  visual  center;  C,  speech  center;  D,  motor  cells  of  speech  nerves  in  the 
spinal  bulb.  Sight  of  dog,  bark  of  dog,  word  "  dog  "  and  sensations  from  speech  muscles  are 
represented  by  arrows  passing  into  the  brain.  The  centers  are  connected  by  association 
fibers,  so  that  when  the  child  has  learned  the  word  "dog"  by  sound  or  when  written,  the 
spoken  or  written  word  calls  up  the  image,  the  sound  of  its  bark  and  the  muscular 
memory  of  how  to  speak  the  word  "  dog.  " 

students  require  eight  hours,  and  this  amount  is  required 
by  most  adults  until  old  age  is  reached.  Repair  being  less 
in  old  age,  less  sleep  is  required. 

569.  The  morning  should  bring  a  feeling  of  vigor.  If 
we  wake  tired  and  discouraged,  there  is  something  amiss. 
It  may  be  that  there  was  over-exertion  the  day  before  and 
the  sleep  has  not  been  long  enough,  or  that  we  have  been 
up  too  late  or  have  eaten  improper  things.  If  the  last  is 
the  case,  there  is  apt  to  be  a  bad  taste  in  the  mouth  on 
awakening.  By  going  to  bed  at  the  same  hour  every 
night,  the  habit  is  formed  of  dropping  off  promptly  and 
soundly  to  sleep.  A  cheerful  state  of  mind  with  resolute 


THE  NERVOUS  SYSTEM 


avoidance  of  worry  promotes  sound  sleep  at  night.  The 
sleeping  room  should  be  cool,  but  it  is  not  necessary  that 
water  freeze  in  the  pitcher.  It 
should  be  well  ventilated,  a  win- 
dow being  left  partly  open  even 
in  moderately  cold  weather  in  the 
northern  states,  and  in  very  cold 
weather  in  the  Gulf  states,  unless 
the  room  is  loosely  built. 

570.  Effect  of  Activity  of  Nerv- 
ous System.  —  If  the  cells  of  any 
tissues  are  not  active,  they  become 
weakened.  It  is  the  same  with 
the  nervous  system.  Fresh  and 
new  sensations  are  necessary  for 
the  health  of  the  brain ;  those 
mental  faculties  that  are  used  be- 
come strong.  Unused  muscles  FIG.  210.— A  study  of  Fatigue. 


flabby     and     ill-nourished     Portions  of  nerve  cells  from  the  spinal 

ganglia.     A,  resting  cell.      £,  cell 

because  the  circulation  in  them 


from  a  ganglion  that  had  been  elec- 
trically eliminated  for  five  hours. 
The  shrinkage  of  the  nucleus  and 
structure  of  the  fatigued  cell  is 
marked. 


is  weakened ;  the  circulation  in 
inactive  nervous  tissue  also  be- 
comes less  active.  Mental  activity 
strengthens  the  nervous  system  and  the  body  in  general. 
If  one  protects  his  sensory  nerves  by  too  warm  clothing 
and  never  lets  the  cold  air  strike  them,  they  become  weak- 
ened and  unreliable  and  allow  the  blood  vessels  to  lose 
tone.  They  are  likely  to  do  strange  things  with  the 
circulation,  causing  colds  and  disease.  If,  because  of 
pulpy  or  soft  food,  the  nerves  of  the  alimentary  canal  are 
not  stimulated  mechanically,  peristalsis  is  weakened  and 
the  intestine  becomes  clogged.  The  loss  of  tone  in  the 
circulation  and  the  sluggish  peristalsis,  with  the  troubles 
that  follow,  can  often  be  cured  by  taking  a  cold  bath  every 
morning.  The  stimulus  to  the  sensory  nerves  spreads 


312  ELEMENTS   OF  PHYSIOLOGY 

reflexly  to  the  vasomotor  nerves  and  to  the  sympathetic 
fibers  of  the  intestine ;  these  are  "  toned  up  "  and  restore 
activity  to  the  involuntary  muscles. 

571.  Connection  of  Body  with  Brain  and  Mind.  —  The 
pulse  rate  is  affected  by  every  emotion.     Shame  causes 
the  blood  vessels  of  the  face  to  dilate.     Painful  emotions 
excite  the  activity  of  the  lachrymal  or  tear  glands.     Joy 
increases  ease  of  movement.     If  an  excited  or  angry  man 
who  is  walking  to  and  fro  sits  down,  his  excitement  de- 
creases.    A  starving  man  and  one  suffering  from   fever 
have  hallucinations.      The   Romans  had  the  proverb  "  a 
sound  mind  in  a  sound  body."     The  care  of  the  body  for 
the  mental  effect  as  well  as  for  the  sake  of  the  body  itself, 
is  only  gradually  regaining  the  high  place  it  held  among 
the  Greeks  and  the   Romans,  a  place  which  it  lost  dur- 
ing the  Dark  Ages.     "  Hysteria  and  nervous  exhaustion 
are  the  fruits  not  of  overwork,  but  of  lack  of  varied  and 
interesting  employment.      The  absurd  opinion  that  hard 
work  is  menial  and  low,  leads  to  most  pernicious  conse- 
quences.     The    girl   who,    turning   from    brain   work   to 
manual  labor,  can  cook,  scrub,  wash,  and  garden,  invites 
the  bloom  of  health  to  her  cheeks ;   while  the  fine  do- 
nothing  lady  loses  her  good  looks,  suffers  from  the  blues, 
and  is  a  nuisance  to  her  friends  and  a  misery  to  herself." 

572.  Two  Kinds  of  Tired  Feeling.  — if  a  person  works 
hard  mentally  or  physically,  the  nutrition   stored  in   his 
cells  is  consumed  by  the  oxygen.      Carbon   dioxid,  urea, 
and  other  products  of  oxidation,  accumulate  ;  this  decreases 
the  production  of  heat,  smothers  the  vital  fire,  as  it  were, 
and  stops  the  setting  free  of  energy.     The  muscles  may 
ache  with  fatigue  or  the  brain  grow  drowsy;   this  is  the 
natural  and  healthful  kind  of  tired  feeling.    It  leads  to  rest 
and  recuperation.     During  the  interval  of  rest,  even  if  no 
new  food  is  absorbed  from  the  canal,  digested  food,  already 
in  the  blood,  and  lymph  are  built  up  into  living  tissue  again, 


THE  NERVOUS  SYSTEM  313 

a  process  called  assimilation.  But  suppose  one  does  not 
work,  but  is  idle,  or  suppose  one  works  with  only  a  small 
part  of  his  bodily  organs  and  forces  the  other  organs  to 
loaf;  the  oxidation  in  the  cells  does  not  take  place  com- 
pletely. Instead  of  urea,  uric  acid  and  other  poisonous 
products  of  incomplete  oxidation  result.  These  poisons 
circulated  by  the  blood  to  the  nerves  can  give  them  a  tired 
feeling  as  effectually  as  hard  work.  Often  with  inactive, 
idle  persons  the  digestion  also  becomes  sluggish,  fermenta- 
tion takes  place  and  the  food  is  changed  to  poisons.  These 
additional  poisons  are  absorbed  by  the  blood  and  carried  to 
the  nerves  to  increase  further  the  tired  feeling.  Some  per- 
sons never  work,  yet  are  always  tired  and  are  said  to  have 
been  "born  tired."  They  belong  to  this  second  class.  If 
they  did  some  honest^  vigorous  work  for  a  few  days,  it  would 
lead  them  to  breathe  deeply  and  freely  and  burn  up  this 
refuse  material.  They  would  again  have  that  self-confident, 
buoyant  feeling  that  all  men  may  have  and  that  every  man 
that  takes  care  of  his  body  does  have. 

573.  The  Source  of  Pain  not  always  where  it  seems  to  be. 
—  When  the  " funny  bone"  is  hit,  the  tingling  is  referred 
to  the  finger,  although,  of  course,  the  pain  is  in  neither 
the  funny  bone  nor  the  finger,  but  in  the  brain.  If  the 
scar  grows  too  tight  over  the  stump  of  an  amputated  arm, 
the  itching  that  seems  to  be  in  the  fingers  may  not  stop 
until  the  scar  is  opened  by  a  new  cut,  and  the  tightness, 
which  is  the  source  of  the  pain,  is  removed.  Some  forms 
of  neuralgic  pains  and  headaches  appear  to  travel  quickly 
from  one  part  of  the  face  to  another.  This  is  because  the 
source  of  the  trouble  is  not  in  the  face  at  all,  but  in  the 
medulla.  Bad  headaches  are  not  so  often  neuralgic  as 
from  other  causes  (Fig.  211).  When  the  spine  is  habitually 
held  crooked,  or,  in  rare  cases,  some  of  the  vertebrae  are 
displaced  by  a  fall  or  jar,  the  circulation  may  be  interfered 
with  near  the  roots  of  the  spinal  nerves,  and  give  the  feel.- 


314 


ELEMENTS   OF  PHYSIOLOGY 


OiSTUfiBANCES  OF 
ftOSE  EAR.  AND 
OCCAYfD  T££TH 


—SPINAL  (MITA7IQH 


FIG.  2ii.— The  Situations  of  Headaches  with 
Relation  to  their  Causes. 

Neuralgic  headaches  (not  marked)  are  believed  to 
arise  from  congestion  in  the  nerve  centers. 


ing  of  pain  in  various  places  in  the  body  where  the  nerves 
terminate ;   for  "  pain  is  the  cry  of  a  starved  nerve  for 

fresh  blood  or  better 
blood."  The  reason  the 
mind  always  refers  the 
pain  to  the  end  of  the 
nerve  is  that  nearly  all 
.-MEWSES  EXHAUSTION  pain  from  a  nerve  does 
come  from  some  irrita- 
tion at  the  end  of  the 
nerve,  and  the  mind  re- 
flexly,  as  it  were,  inter- 
prets the  pain  as  coming 
from  its  usual  source. 
When  the  position  is  cor- 
rected, the  circulation  is 
freed  and  relieves  the 
nervous  system.  Downward  displacement 
of  the  abdominal  organs  may  cause  pressure 
upon  some  of  the  sympathetic  nerves  and 
ganglia  and  cause  pain  and  derangement  of 
different  organs.  What  causes  the  foot  to 
"go  to  sleep"?  Can  you  explain  the  self- 
deception  in  "  Aristotle's  experiment "  (Fig. 
212)? 

574.  Effects  of  Alcohol  on  the  Nervous  Sys- 
tem. —  As  alcohol  acts  on  many  organs 
through  its  action  on  the  nervous  system, 
it  would  naturally  be  supposed  that  the  nerv- 
ous matter  itself  would  be  injured,  and  such 
is  the  case.  In  fact,  it  is  upon  the  delicate 
nervous  system  that  its  most  destructive  ef- 
fects are  wrought.  One  of  the  first  effects  of 
alcohol  is  a  flushing  of  the  face  and  a  feeling 

&  FIG.  212.  — Aristotle's 

of  warmth  on  the  surface  of  the  body.     This        Experiment. 


THE  NERVOUS  SYSTEM  315 

is  due  to  the  quickened  action  of  the  heart  and  the  dilatation 
of  the  small  blood  vessels  from  the  effects  of  alcohol  on  the 
nerve  centers  controlling  these  organs.  The  mind  is  at  first 
more  active,  because  the  little  vessels  of  the  brain  are  dilated 
and  blood  is  sent  more  freely  to  that  part.  A  little  later  the 
alcohol  begins  to  disturb  the  reflex  and  coordinating  powers 
of  the  nervous  system,  and  ordinary  muscular  movements 
are  performed  imperfectly  and  with  difficulty.  The  nerve 
centers  seem  to  be  attacked  and  paralyzed  progressively 
by  alcohol,  beginning  with  the  highest  and  proceeding 
toward  the  lowest.  The  will  power  and  judgment  first 
become  paralyzed,  and  only  the  emotional  and  impulsive 
instincts  of  human  nature  are  left ;  these,  being  no  longer 
under  control  of  the  higher  faculties  of  reason  and 
judgment,  are  likely  to  cause  the  individual  to  act  in  an 
irrational  manner.  In  the  last  stages,  consciousness  and 
volition  are  lost,  and  only  that  part  of  the  nervous  system 
in  the  medulla  which  governs  circulation  and  respiration 
remains  active.  In  other  words,  the  man  is  "  dead  drunk." 
A  large  quantity  of  alcohol  may  produce  death  by  paralyz- 
ing even  these  nerve  centers,  thus  stopping  all  organic 
functions.  This  overaction  and  irregular  action  of  the 
nerves,  when  repeatedly  occurring,  has  the  effect  finally 
of  deforming  or  destroying  the  nerve  tissues  (Fig.  191). 
575.  There  is  scarcely  a  nervous  disease  known  to 
science  that  the  use  of  alcoholic  liquors  may  not  bring  on 
or  aggravate.  General  debility,  neuralgia,  insomnia,  epi- 
lepsy, paralysis  of  every  form  and  type,  insanity  in  all 
its  grades,  as  well  as  delirium  tremens,  may  find  in  alcohol 
their  exciting  and  predisposing  cause.  But  the  worst  of  all 
of  the  effects  of  its  long-continued  use  is  upon  the  morals. 
The  brain  degenerates  and  the  mind  loses  control  over  the 
appetite.  Pledges  of  total  abstinence,  fear  of  disgrace, 
loss  of  social  position,  loss  of  friends  and  family,  apprehen- 
sions for  this  world  or  the  next,  —  all  these  considerations 


316  ELEMENTS   OF  PHYSIOLOGY 

have  no  more  weight  against  this  disease  of  chronic  alco- 
holism, than  they  would  have  against  smallpox  or  typhoid 
fever. 

576.  Subjects  for  Compositions.  — Prevention  better  than 
Cure.  Habits.  Sunshine.  Natural  Cures  and  Medicines. 
The  Influence  of  the  Digestive  Organs  upon  the  Other 
Organs.  The  Influence  of  the  Muscles  upon  the  Other 
Organs.  The  Influence  of  the  Blood  upon  the  Body.  The 
Influence  of  the  Nervous  System  upon  the  Other  Organs. 
Heredity.  The  Causes  of  Disease.  The  Rewards  of 
Right  Living.  The  Influence  of  the  Body  upon  the  Mind. 
The  Body  a  Temple.  Housekeeping.  The  Way  of  the 
Transgressor  is  Hard.  Nature  as  a  Physician.  Health 
and  the  Disposition.  The  Mind  and  Health.  Wonders 
of  the  Body.  Mysteries  of  the  Body.  What  Fools  these 
Mortals  Be.  Health  Fads.  Medicine  Crazes.  Exposure 
and  Coddling.  Pampering  and  Hardening.  The  Blessings 
of  Temperance.  Effects  of  Use.  Effects  of  Disuse. 
Why  are  we  Sick  ?  Adam's  Apothecary  Shop. 

577-  Phrenology.  —  There  is  a  fantastic  theory  called  phrenology 
that  young  people  should  learn  to  estimate  correctly.     It  is  based  on 
dividing  the  head  by  guesswork  into  sections  supposed  to  be  the  seats 
of  the  various  attributes  of  the  mind,  such  as  firmness,  benevolence, 
self-esteem,  acquisitiveness,  and  what  not.     This  attempt  at  science 
was  made  over  a  century  ago,  and  it  has  been  known  for  a  hundred 
years  to  be  nonsense.     But  it  is  turned  to  financial  profit  by  charlatans, 
who  take  advantage  of  the  unlearned  seeking  a  short  cut  to  science. 
Bumps  on  the  head,  instead  of  indicating  the  presence  in  the  brain  of 
more  gray  matter,  are  due  in  many  places  to  thickening  of  the  bone,  or 
to  air  spaces  in  the  bone.     Phrenology  belongs  in  the  realm  of  ex- 
ploded sciences  along  with  astrology,  or  reading  one's  future  in  the 
stars  ;  palmistry,  or  telling  the  fortune  by  reading  the  lines  in  the  hand ; 
and  alchemy,  or  the  search  for  the  philosopher's  stone,  which  was  to 
turn  everything  it  touched  into  gold. 

578-  Hypnotism,  etc.  —  Even  when  awake  our  actions  are  largely 
controlled  by  the  suggestions  or  influence  of  others.     Although  we  are 
awake,  this  influence  is  largely  unconscious.     But  if  one  goes  to  sleep 


THE  NERVOUS  SYSTEM 

at  the  suggestion  of  another  and  while  hearing  his  voice  and  believing 
in  his  power  to  influence,  the  subjection  to  that  influence  continues 
during  the  sleep  which  follows.  This  sleep  seems  to  be  a  kind  of 
induced  somnambulism.  That  there  is  no  animal  magnetism  concerned 
is  shown  by  the  fact  that  the  most  delicate  electrical  instruments  fail  to 
show  the  faintest  disturbance.  Frequent  repetition  of  the  hypnotic  con- 
dition is  believed  by  some  to  weaken  the  will  of  the  individual.  The 
nature  of  the  hypnotic  condition  is  not  fully  settled.  Like  other  sub- 
jects on  which  science  is  unable  to  pronounce  a  definite  verdict,  this 
whole  subject  has  been  surrounded  by  rogues  with  humbuggery  and 
quackery.  Some  persons  by  practice  can  read  the  intended  movements 
of  another  by  grasping  the  hand  of  the  other  with  his  arm  held  in  an 
unstable  position.  This  muscle-reading  is  based  upon  the  fact  that 
when  the  mind  is  concentrated  on  making  a  certain  movement,  the 
muscles  will  resist  an  opposite  movement.  Again,  the  mystery  of 
ordinary  sleep  has  never  been  solved.  It  is  not  surprising  that  its 
variations,  such  as  trances,  somnambulism,  and  the  hypnotic  sleep,  are 
not  understood.  The  relation  of  mind  and  matter,  the  connection  of 
the  soul  and  body,  are  mysteries  that  may  be  beyond  the  power  of  man 
ever  to  solve. 

APPLIED   PHYSIOLOGY 
EXERCISE  I 

1.  Why   is  playing  the   organ  less   trying  to  the  nerves  of  the 
player  than  playing  the  piano? 

2.  Why  is  it  best  to  change  from  very  absorbing  work  to  work 
of  less  interest  a  while  before  retiring  ? 

3.  Why  is  the  power  of  habit  a  blessing?     A  danger? 

4.  How  does  travel  often  cure  a  sick  person  when  all  else  fails? 

5.  Why  should  we  never  study  immediately  after  eating? 

6.  Why  is  working  more  healthful  than  "  taking  exercise  "  ? 

7.  Is  it  better  for  children  to  play  or  to  take  exercise? 

8.  What  causes  the  peristaltic  action  of  the  stomach? 

9.  Is  one  more  likely  to  sleep  soundly  who  does  his  brain  work 
in  the    forenoon    and    muscular  work   in   the   afternoon   than   if  he 
reverses  the  order? 

10.  Why  can  one  walk  and  carry  on  a  conversation  at  the  same 
time? 

EXERCISE  II 

11.  How  does  indigestion  cause  a  headache? 

12.  Does  perfectly  comfortable  clothing  from  head  to  foot  contribute 
to  one's  ease  in  company? 


318  ELEMENTS   OF  PHYSIOLOGY 

13.  Does  uncomfortable  clothing  make  one  self-conscious? 

14.  Is  it  as  important  to  have  the  shoes  and  the  clothing  perfectly 
comfortable  when  going  out  as  when  staying  at  home? 

15.  Would  you  get  more  rest  by  sleeping  for  four  hours  undisturbed, 
or  by  sleeping  eight  hours  but  being  awakened  every  half  hour  by  some 
noise  and  going  immediately  to  sleep  again  (§  567)  ? 

1 6.  When  one  sits  with  the  leg,under  the  body,  why  is  it  that  the 
compression  causes  a  tingling  sensation  or  paralyzed  feeling  in  the  foot  ? 

17.  When  one's  finger  is  cut,  where  is  the  pain? 

18.  Why  does  a  hand  still  seem  to  itch  after  it  is  amputated? 

19.  Does  the  act  of  assuming  artificial  positions  like  the  "straight- 
front"  tend  to  make  one  stiff  or  graceful,  self-conscious  or  spontaneous? 

20.  Do  the  girl  who  frets  over  washing  the  dishes,  working  with  an 
unwilling  mind,  and  the  boy  who,  while  he  is  sawing  wood,  is  wishing 
to  go  to  a  baseball  game,  do  their  work  with  more  or  less  fatigue  than 
if  they  worked  cheerfully  and  willingly  ?    Why? 

EXERCISE    III 

21.  How  is  a  sneeze  a  protective  act  ? 

22.  Why  may  a  dyspeptic  digest  a  large  Thanksgiving  or  Christ- 
mas dinner  when  he  often  has  trouble  with  an  ordinary  dinner? 

23.  Why  is  it  more  difficult  for  an  adult  to  learn  to  speak  a  language 
than  for  a  child?    Why  do  adults  find  drawing  and  languages  more 
difficult  to  acquire  than  history  and  mathematics  (§  546)? 

24.  In  what  two  ways  may  opening  a  window  when  a  student  is 
becoming  dull  and  drowsy  at  his  books  enable  him  to  wake  up  and 
study  with  ease? 

25.  What  is  the  basis  of  the  saying  among  mothers  that  a  "  croupy  " 
child  can  be  cured  of  the  tendency  by  being  allowed  to  go  barefoot  a 
great  deal  ? 

26.  Did  you  ever  know  any  person  to  whom  the  terms  "afflicted  by 
the  disease  of  work"  applied?    Also  the  opposite,  "  disease  of  idleness"? 

27.  Muscles  may  be  classed  as  minor,  such  as  those  of  the  eye, 
voice,  hand ;  and  major,  such  as  those  of  upper  arm,  leg,  trunk.     Why 
is  the  use  of  the  minor  muscles  exhausting  to  the  nerves,  while  the  use 
of  the  major  muscles  strengthens  the  nerves  (§§  227,  234)  ? 

28.  What  kind  of  cells  shrivel  like  a  baked  apple  when  they  become 
fatigued  (Fig.  210)  ? 

29.  A  nerve  or  nerve  fiber  does  not  become  tired  or  fatigued  in  any 
way.     What   do   we   mean  when   we  say  the   nerves   are  worn  out 
(Fig.  210)? 


THE  NERVOUS  SYSTEM  319 

30.  Why  do  you  throw  cold  water  upon  a  fainting  person? 

31.  Nightmares  are  caused  by  poor  circulation  of  the  blood  about 
the  solar  plexus,  which  is  just  behind  the  stomach.     Explain  how  sleep- 
ing on  the  back  may  bring  them  on.     How  eating  a  heavy  supper  may 
cause  them. 

32.  What  is  the  effect  of  a  thin  skin  and  of  a  thick  skin  upon  the 
disposition  of  a  person  ? 

33.  Why  may  cold  feet  cause  sleeplessness? 

34.  Why  does  constant  moderate  drinking  undermine  the  health 
more  than  occasional  intoxication? 

35.  The  vasomotor  nerves  control  the  size  of  the   blood  vessels. 
Which  nerve  centers  control  these  nerves  ?    Why  does  a  draught  blow- 
ing on  the  back  of  the  neck  often  cause  a  cold  (Fig.  200)  ? 


CHAPTER   XVII 

SOME  SPECIAL  REGULATIVE  PROCESSES 

REGULATION  OF  TEMPERATURE 

579.  Necessity  for  Regulation.  —  Man  lives  in  the  torrid 
zone  and  in  the  frigid  zone,  yet  his  temperature  remains 
the  same  as  he  goes  from  one  zone  to  another,  and  as 
summer   changes    to   winter.      The    temperature    of    the 
healthy   body  is  about  98.6°   F.      This  is    unmistakable 
evidence    that    some    means    of    maintaining    a    uniform 
temperature    exists    in    his    body.      The   wonderful    ease 
with  which  the  human  body  maintains  a  normal  tempera- 
ture when  exposed  to  extremes  of  heat  and  cold  is  a  fasci- 
nating and  instructive  subject  for  study;   but  it  remains 
partly  a  mystery,  and  the  mechanism  by  which  this  end  is 
attained  has  never  been  fully  explained. 

580.  The  Highest  Temperature  which  living  tissue  may 
reach  without  destroying  life  is  113°  F.,  but  it  could  remain 
at  such  a  temperature  only  a  short  time.1    "A  man  can 
for  a  short  time   remain   in    an  oven  heated  to  the  boil- 
ing point  of  water  (212°  F.),  provided  the  air  is  dry.    With 
felt  slippers  on  his  feet  he  could  stand  there  while  his  dinner 
cooked  beside  him.     He  is  able  to  do  this  owing  to  the  pro- 
fuse perspiration  which  pours  from  his  skin  and  cools  his 
body  by  evaporation.     If  the  oven  were  full  of  steam,  the 

1  Once  a  man  took  the  pulse  of  his  daughter  who  was  ill,  and  found  it  to  be 
1 20.  He  was  greatly  alarmed,  and  summoned  several  physicians.  He  had 
confused  the  pulse  with  the  temperature.  The  pulse  rate  during  vigorous 
exercise  sometimes  reaches  160  per  minute. 

320 


SOME   SPECIAL   REGULATIVE  PROCESSES  $21 

man  would  be  instantly  killed,  because  evaporation  of  the 
sweat  would  be  prevented"  (Leonard  Hill,  M.  D.).  If 
the  cells  of  either  plant  or  animal  life  be  subjected  to  a 
temperature  of  114°  or  over,  the  life  of  the  protoplasm  is 
destroyed  beyond  recovery. 

581.  Breathing  and  the  Temperature.  —  Since  oxygen  is 
the  supporter  of    combustion  and  carbon  dioxid    retards 
combustion,  the  quantity  of  oxygen  and  carbon  dioxid  in 
the  body  affects  the  temperature.     When  the  body  is  at 
an  abnormally  high   temperature,   as  during  a  fever,  the 
breathing  is  generally  more  vigorous  than  usual.     Those 
animals,  such  as  the  bat,  that  hibernate  and  go  without  food 
in   cold  weather,   cease  breathing   altogether   during  the 
trancelike  condition,  and  their  temperature  sinks  nearly  to 
freezing  point.     The  absence  of  the  oxygen,  other  than 
what  may  diffuse  through  the  windpipe  into  the  motionless 
lungs  or  through  the  skin,  and  the  accumulation  of  carbon 
dioxid,  cause  the  fire  of  life  to  sink  very  low. 

582.  The  Source  of  Animal  Heat  is  the  combustion  of  the 
food  in  the  body  by  the  oxygen.     Wherever  cell  activity 
is  taking  place,  heat  is  produced.     The  muscles  are  the 
greatest  heat  producers  of  all  the  organs.     Their  activity 
gives  rise  to  one  half  the  heat  of  the  body.     A  frog's  body 
keeps  at  the  temperature  of  the  surrounding  objects  in 
winter  and  summer.    He  cannot  stand  the  heat  of  summer 
and  retires  to  a  cool  ditch  or  well.     In  winter  he  buries 
himself  to  escape  the  cold.     He  is  stimulated  by  warmth 
and  benumbed  by  cold.     Man    and   other  warm-blooded 
animals,  on  the  contrary,  are  stimulated  by  cold  and  are 
less  active   during  warm  weather.     The   temperature   of 
birds  is    104°.     A  chick  before  hatching  is  like  a  cold- 
blooded animal.     As  soon  as  it  begins  to  peck  its  way  out 
of  the  shell,  it  begins  to  acquire  the  power  of  regulating 
its  temperature  ;    the  power  may  be  acquired   in    a  few 
minutes.     This  new  power  comes  from  the  new  muscular 

Y 


322  ELEMENTS   OF  PHYSIOLOGY 

activity  of  the  chick,  the  beginning  of  the  habit  of  breath- 
ing, and  the  drying  of  its  downy  feathers. 

583.  The  Loss  of  Heat  occurs  by  conduction  through  the 
skin,  also  by  the  evaporation  of  water  from  the  skin  and 
lungs,  and  by  the  taking  in  of  cool  food,  drink,  and  air. 

584.  How  the  Nerves  regulate  the  Heat.  —  The  tempera- 
ture of  the  body  is  raised  by  increasing  the  heat  produc- 
tion, or  by  diminishing  the  loss  of  heat.     The  temperature 
is  lowered  by  the  opposite  processes.     There  are  believed 
to  be  three  classes  of  nerve  centers  to  regulate  the  pro- 
cesses.    One  class  of  centers  in  the  brain  when  stimulated 
by  cold  causes  the  heat  production  to  increase ;    another 
class  when  stimulated,  causes  heat  production  to  diminish. 
The  third  center  is  in  the  spinal  cord  and  is  automatic,  but 
may  be  influenced  by  the  centers  in  the  brain.     We  should 
be  in  danger  of  being  killed  by  the  cold  long  before  the 
thermometer  reached  the  freezing-point,  if  it  were  not  true 
that  cold,  in  whatever  form  it  may  be  applied,  starts  im- 
pulses in  the  skin  which  excite  the  tissues  that  generate 
heat,  so  that  there  is  increased  production  of  heat. 

585.  The  Distributor  of  Heat  generated  by  the  active 
organs,  to  the  resting  organs,  is  the  blood.      The  blood 
also  causes  heat  to  leave  the  body,  giving  it  off  while  pass- 
ing through  the  blood  vessels  of  the  skin. 

586.  How  does  perspiration  cool  the  body  ?     Why  is  it 
an  advantage  for   you  to  shiver  and  for   your   teeth  to 
chatter  when  you  are  very  cold  ?     Why  is  it  an  advantage 
for  the  skin  to  turn  pale  when  one  goes  out  into  a  cold 
wind  ?     What  effect  upon  perspiration  does  the  blanching 
of  the  skin  have  ?      What  effect  does  the  blanching  have 
upon  the  loss  of  the  heat  of  the  body  from  the  contact 
with  the  cold  air  ? 

587.  Clothing  conserves  the  heat  of  the  body,  but  cannot 
generate  it.     Such  heat  arises  from  the  combustion  in  the 
system  of  the  food  by  the  oxygen  of  the   air.      In   hot 


SOME   SPECIAL  REGULATIVE  PROCESSES  323 

weather  the  body  naturally  requires  less  heat  than  in  colder 
seasons;  hence  less  food,  especially  fats  and  sugars,  are 
consumed  in  summer  than  in  winter,  in  the  tropics  than  in 
temperate  or  frigid  regions.  Suppose  you  have  changed 
your  clothing  in  summer  to  the  very  coolest,  and  are  still 
oppressed  by  the  heat,  what  changes  should  you  make  in 
your  diet  ?  Suitable  food  eaten  in  moderation  adds 
greatly  to  one's  comfort  in  warm  weather,  and  enables 
one  to  work  with  energy  and  pleasure,  but  partaking 
abundantly  of  heating  foods  renders  all  exertion  dis- 
agreeable. 

REGULATION  OF  THE   STORE  OF  ENERGY 

588.  Fatigue.  —  You  learned  in  the  chapter  on  stimu- 
lants and  narcotics  that  a  man  has  energy  stored  up  suffi- 
cient to  support  him  for  a  certain  number  of  days  without 
food.     (How  many   days  ?)     Stored   energy  is  simply  a 
store  of  food  and  oxygen  in  the  tissues.     The  nervous  sys- 
tem so  acts  as  to  prevent  any  undue  exhaustion  of  that 
supply  from  taking  place.     When  the  brain  is  long  active, 
fatigue  and  sleepiness  ensue.     When  the  muscles  are  long 
active,  fatigue  and  aching  ensue.     The  wise  person  rests 
in  each  case.     These  warnings  come  before  the  exhaus- 
tion  has   progressed  to  an    injurious  degree.     They  are 
caused  by  the  accumulation  of  the  products  of  combustion 
in  the  tissues.     These  products  affect  the  nerves  and  the 
warning  is  thus  given. 

589.  In  what  other  way  besides  by  work  may  poisons 
accumulate  so  as  to  cause  a  feeling  of  exhaustion  and  lack 
of  energy  ?     What  are  the  two  kinds  of  tired  feeling  of 
which  you  learned  ?      Has  a  person  any  more  right  to 
injure  his  own  body  or  allow  diseased  conditions  to  come 
to  it  than  he  has  to  injure  the  body  of  another  ? 

590.  Improvidence. — Just  as  there  are  many  persons  who 
cannot   keep   financial    capital    ahead    sufficient   for   one 


324  ELEMENTS   OF  PHYSIOLOGY 

month's  needs,  so  there  are  many  people  who  cannot  keep 
physical  capital  in  their  bodies  sufficient  for  forty  days 
ahead.  This  is  the  amount  that  every  sound  person 
should  have.  They  expend  their  energy  until  they  are 
"worn  out"  temporarily,  or  they  neglect  proper  care  of 
their  bodies  so  that  the  mechanism  does  not  work  properly, 
their  energy  is  diminished,  and  they  become  depressed. 
When  one  is  depressed  and  exhausted  from  overwork 
or  improper  working  of  the  physical  organism,  his  first 
care  should  be  to  restore  the  strength.  Rest  will  often 
accomplish  it,  but  many  persons  are  not  wise  enough  to 
observe  this ;  they  have  a  mistaken  notion  of  the  nature  of 
stimulants  and  of  the  bodily  strength.  They  arouse  the 
nerves  to  renewed  action  by  taking  poisons;  activity 
ensues  that  leads  to  expenditure  of  a  part  of  the  precious 
strength  remaining.  A  drunkard  during  a  period  of  in- 
toxication often  keeps  up  this  course  until  his  strength  is 
exhausted.  He  is  physically  bankrupt;  then  he  stops. 
After  a  few  weeks  or  months  of  soberness,  during  which  the 
organs  have  stored  up  energy  again,  he  begins  to  apply 
poisonous  stimulants  to  enable  him  to  use  up  this  strength 
and  becomes  physically  bankrupt  again,  thus  proving  him- 
self unworthy  to  have  as  much  capital  intrusted  to  him  as 
is  intrusted  to  other  men. 

591.  Are  Feelings  always  a  Reliable  Guide  ?  —  Feelings 
may  be  deceptive,  not  only  when  the  nerves  are  confused 
by  stimulants,  but  also  as  the  result  of  bad  habits.  A  man 
who  has  stooped  over  a  book  or  desk  all  day  does  not  feel 
like  doing  muscular  work,  yet  it  is  the  very  thing  he  needs 
to  expand  those  flattened  lungs  that  brought  the  feeling  of 
fatigue.  If  one  habitually  overeats,  it  may  cause  a  gnaw- 
ing at  the  stomach  that  gives  him  a  desire  to  continue 
the  habit.  After  using  alcohol  or  tobacco,  a  desire  for 
these  worst  enemies  of  the  body  is  implanted.  The  body 
seems  to  acquire  injurious  habits  and  desires  almost  as 


SOME  SPECIAL  REGULATIVE  PROCESSES  325 

readily  as  healthy  ones.  The  warnings  against  destructive 
acts  come  at  first.  If  the  warnings  are  disregarded,  natural 
instincts,  those  heaven-sent  guardians  of  our  welfare,  with- 
draw, and  evil  habits  and  desires  assume  control. 

592.  Natural  and  Artificial.  —  Everything  in  the  world  is 
natural.     We  and  our  most  artificial  acts  are  a  part  of 
nature.     That  which  comes  by  nature  apart  from  man,  or 
that  which  he  does  truthfully  copying  nature,  is  usually 
called  natural.     That  which  is  done  by  man  in  such  a  way 
as   to  disregard   the  usual  processes  of  the  rest  of   the 
natural  world,  is  called  artificial.     Artificiality  is  usually 
marked  by  ugliness  and  weakness,  but  it  is  not  recognized 
as  such  by  any  one  whose  taste  has  become  depraved  from 
following  artificial  customs. 

DISEASE 

593.  Use  of  Pain  and  Disease.  —  Most  diseases  have  for 
their  purpose  to  repair,  to  protect,  or  to  purify.     If  the 
body  can  set  to  work  to  repair  a  cut  in  the  flesh  or  a 
broken  bone,  how  much  more  easily  can  it  purify  unsound 
organs  or  tissues  and  make  them  sound  again.     It  used  to 
be  the  custom  to  apply  liniments  and  healing  ointments 
to  wounds  and  broken  bones  to  assist  in  the  healing,  but 
now  it  is  found  that  to  set  the  bone  and  bind  the  edges  of 
the  wound  together  is  sufficient.     If  kept  clean  and  undis- 
turbed, nature  will  work  a  perfect  cure. 

594.  Sometimes  Poisons  accumulate  in  the  body  and  in- 
terfere with  the  working  of   the   organs.     This   may  be 
caused  by  drinking  poisonous  substances,  or  using  them  as 
food,  or  by  indigestion,  in  which  case  germs  may  find  sus- 
tenance and  multiply,  giving  poisons  into  the  circulation. 
The  automatic  regulative  apparatus  of  the  body  is  usually 
equal  to  the  difficulty.     These  poisons  are  oxidizable,  es- 
pecially at  a  little  higher  temperature  than  that  which  the 


326  ELEMENTS   OF  PHYSIOLOGY 

body  usually  has.  So  nature  sets  to  work  to  create  more 
heat  in  the  body  and  literally  to  burn  up  the  poisons.  If 
the  impurities  are  in  one  place,  as  in  a  joint  or  in  the 
throat,  there  arises  local  heat,  called  inflammation.  If  the 
poisons  are  distributed  in  the  body,  a  more  general  heat, 
called  a  fever,  may  begin. 

Fever  in  itself  is  harmless  and  should  not  be  combated 
unless  very  high  and  of  long  duration,  under  which  con- 
ditions it  may  destroy  the  tissues.  Fever  is  nature's  method 
of  ridding  the  body  of  poisons  which,  if  allowed  to  accumu- 
late indefinitely,  may  produce  death  or  permanent  weak- 
ness. One  who  has  fever  should  avoid  using  strong 
remedies  to  lower  the  temperature,  unless  the  fire  that 
is  burning  up  the  rubbish  threatens  to  destroy  the  house 
also.  While  a  fever  is  in  progress,  nature  takes  away 
the  appetite  to  prevent  adding  fuel  to  the  flame;  takes 
away  the  inclination  to  move,  as  the  exercise  would  be 
carried  on  by  combustion  in  the  muscles ;  gives  great 
thirst  for  cold  water,  which  cools  the  body  and  dissolves 
the  poisons,  and  adds  to  the  activity  of  the  kidneys  in  ex- 
creting the  products  of  the  combustion.  In  former  days, 
when  nature  was  entirely  distrusted,  a  patient  burning 
with  fever  was  not  allowed  a  drink  of  cold  water,  as  it  was 
supposed  it  would  kill  him.  (Read  notes  I  and  2,  page 

329.) 

595.  If  a  grain  of  sand  gets  into  the  eye,  nature  first 
causes  pain  to  prevent  winking  the  lid  and  injuring  the  eye, 
and  then  produces  tears  which  tend  to  wash  out  the  sand. 

If  a  boy  eats  green  apples,  he  has  colic,  which  should 
teach  him  to  wait  next  time  until  they  are  ripe.  He 
has  taken  indigestible  things  into  his  stomach,  and  the 
stomach,  acting  for  his  welfare,  under  the  direction  of  the 
nervous  system,  ejects  the  food.  When  a  person  habitually 
partakes  of  things  which  are  irritating  to  the  stomach  and 
injurious  to  its  delicate  lining,  nature  creates  mucus  to 


SOME  SPECIAL  REGULATIVE  PROCESSES  $2? 

lubricate  or  oil  the  lining,  so  that  the  mucous  membrane 
may  not  suffer  serious  damage.  In  this  way  arises  catarrh 
of  the  stomach,  which  is  very  disagreeable,  but  is  a  pro- 
tective and  curative  process. 

596.  A  man  has  painful  gout  in  a  joint;  what  is  the 
matter  ?     The  man  did  not  burn  up  by  honest  muscular 
work  the  food  he  ate,  and  it  turned  into  poisonous  acid, 
which  collected  in  the  loose  spaces  around  the  joint.     The 
natural  regulative  power  of  the  body  forces  that  man  to 
rest,  by  sending  a  pain  every  time  he  moves  actively,  in 
order  to  prevent  damaging   the  joint  by   moving  it  too 
much  while  the  inflammation  is  burning  up  the  poison.    If 
the  man  were  allowed  to  exert  himself  actively,  uncon- 
scious of  the  damage,  the  joint  would  soon  be  destroyed. 
(Read  note  3,  page  330.) 

597.  Indigestion  is  another  trouble  that  is  usually  mis- 
understood.    If  one  suffers  from  "biliousness,"  the  liver 
is  at  once  blamed,  when  usually  the  liver  has  nothing  to 
do  with  it.     You  learned  that  the  condition,  as  a  rule,  re- 
sults from  taking  food  into  the  stomach  out  of  all  propor- 
tion  to   the   work   its   owner   does ;  or,  in  warm    spring 
weather,  from  eating  enough  to  keep  one  warm  in  freezing 
weather.     Then  follows  a  combination  of  symptoms  which, 
at  a  guess,  is  called  biliousness,  —  loss  of  appetite,  nausea, 
headache,  loss  of  energy.     The  first  symptom  is  sent  be- 
cause nature  insists  on  giving  the  stomach  a  rest  when  it 
is  incapable  of  digesting ;  the  nausea  may  produce  vomit- 
ing to  expel  the  offending  substance.     The  headache  and 
loss  of  energy  are  to  prevent  exercise  that  would  stir  up 
the  circulation  and  distribute  the  poisons  throughout  the 
body  before  the  proper  organs  could  dispose  of  them. 

598.  One  who   is    suffering   from   nervous  exhaustion, 
unable    to   do    anything   whatever,    abhors    the    idea    of 
working  or  attending   to  business;    but   the   presence  of 
this  symptom  is  a  protection.     If  the  individual  were  not 


328  ELEMENTS   OF  PHYSIOLOGY 

forced  to  rest,  he  might  continue  at  his  business  and  com- 
plete the  exhaustion. 

599.  Symptoms  and  the  Disease.  —  A  distinction  should 
be  made  between   the  symptoms  and   the  disease.     The 
symptoms  are  to  warn  the  patient  to  allow  the  curative 
process  to  go  on,  and  they  should  not  be  combated.     If  a 
log  fell  on  a  man  and  he  yelled  aloud,  would  it  suffice  to 
stuff  a  handkerchief  into  his  mouth  ?     No,  the  important 
thing  would  be  to  remove  the  log.     If  you  have  a  head- 
ache, the  quickest  way  to  relief  is  to  take  antikamnia,  or 
some  of  the  other  poisonous  coal-tar  compounds,  or  per- 
haps morphine.     But  if  you  do  not  wish  to  cause  further 
injury  to  the  body,  drink  plenty  of  water  to  cleanse  the 
stomach,  if  the  trouble  is  there,  or  go  out  and  breathe  fresh 
air  and  rest  the  mind,  if  the  trouble  is  mental.     If  you  had 
a  corn  on  the  toe,  would  you  burn  it  off  with  salicylic  acid 
only  to  have  it  come  back,  or  would  you  wear  comfortable 
shoes   so   that   the   corn   would   go   away   of   itself  ?      If 
the  cause  were  not  promptly  removed,  the  corn   might 
become  so  deeply  rooted  that  it  would  be  very  slow  to 
leave. 

600.  Remove  the  Cause  of  the  disease,  and  the  symptoms 
usually  disappear  of  themselves.      It   is  said  that  there 
are   one   thousand    seven    hundred   diseases.     There   are 
hardly  more   than   half   a   dozen  ways  of   getting   sick; 
errors  in  diet  and  dress,  poor  ventilation,  overwork,  under- 
work, exposure,  worry,  are  the   underlying  causes  of  all 
diseases.     The  ways  of    getting   well   are   likewise   few. 
Correct   the   habits    of    eating   and    drinking,    avoid    poi- 
sons, work  enough  but  not  too  much,  breathe  clean  air, 
keep  the  body  clean  and  free  enough  for  perfect  ease 
of  movement,  and  keep  the  mind  contented,  —  these  arc 
the  first  laws  of  healing.     (Read  notes  5  and  6,  page  332.) 

601.  What  common  drug  causes  insalivation  (uncontrol- 
lable flow  of  saliva  for  a  time)  with  loss  of  most  of  the 


SOME  SPECIAL  REGULATIVE  PROCESSES  329 

teeth,  and  weakness  for  life  ?  Do  these  evil  effects  occur 
more  often  when  the  drug  is  prescribed  by  a  physician,  than 
by  one  of  the  self-appointed  home  doctors  that  recklessly 
tinker  with  the  health  of  family  and  friends  ?  What  com- 
mon drug  causes  defective  hearing  and  deafness?  Whether 
the  trouble  is  located  in  the  heart  or  the  stomach,  or  the 
feet  or  the  head,  what  organ  must  always  bear  the  burden 
of  taking  the  medicine  into  the  system  ?  How  is  dyspepsia 
caused  by  drugs  ?  Which  system  first  becomes  diseased 
from  frequent  use  of  stimulant  or  narcotic  drugs?  Is  it 
easier  to  prevent  sickness  by  hygiene  than  to  cure  it? 
Did  you  ever  know  of  any  one  who  took  better  care  of  his 
horse  than  he  did  of  himself  ?  If  Dr.  Tanner  had  worked 
hard  during  his  fast,  what  would  have  been  the  result  ? 

NOTES 

i.  Treatment  for  a  Cold.  —  Rest ;  sleep;  a  light  diet  of  toasted 
bread,  and  fruits.  This  may  be  followed  by  a  hot  mustard  foot-bath, 
the  patient  drinking,  meanwhile,  several  glasses  of  hot  water  to  start  a 
free  perspiration  and  open  the  pores  of  the  body.  Thus  impurities  are 
gotten  rid  of  and  the  circulation  of  the  blood  is  restored.  After  the  feet 
have  been  soaked  in  hot  water  for  ten  or  fifteen  minutes,  immerse  them 
for  a  second  in  cold  water  and  dry  with  a  rough  towel  The  patient 
should  go  immediately  to  bed.  It  is  well  to  provide  a  rubber  bag  of 
hot  water  or  a  hot  brick  for  the  feet. 

2.  Approach  of  a  Cold.  —  On  the  threatened  approach  of  a  cold,  the 
nose  should  be  kept  clear  at  all  hazards,  by  frequently  blowing  it  in  such 
a  way  as  to  cause  as  little  irritation  as  possible,  and  by  keeping  the  mouth' 
tightly  closed,  drawing  every  breath  through  the  nose.  This  treatment 
often  averts  the  cold,  provided  chilling  or  overheating  of  the  body  is 
avoided  for  a  time,  the  body  being  naturally  more  susceptible  to  draughts 
or  to  any  kind  of  exposure,  than  it  is  at  other  times.  The  coming  of 
a  cold  is  often  made  known  by  a  slight  hoarseness.  There  may  yet  be 
time  promptly  to  moderate  the  diet,  or  cease  the  exposure,  or  change 
the  bad  habit,  which  is  bringing  on  the  cold.  Omitting  a  meal  may  do 
good  now  when  it  would  accomplish  little  if  tried  later.  Why  are  colds 
caused  more  quickly  by  draughts  on  a  part  of  the  person  than  by  draughts 
that  blow  on  the  whole  body  ?  Question  for  discussion  :  Should  the  vital 


330  ELEMENTS  OF  PHYSIOLOGY 

organs  or  the  limbs  be  the  more  warmly  clothed  if  there  is  any  difference 
between  the  protection  given  them  ?  Suggestions  :  Distance  from  heart, 
delicacy,  natural  activity  of  circulation,  effect  of  exercise.  (Read  note  7, 
page  332.) 

3.  Chronic   Rheumatism.  —  Wherever  it  is   located,   the    general 
treatment  should  be  about  the  same.     You  must  improve  the  general 
health.     You   must  use  the   muscles  of  the   entire   body,  moderately, 
daily,  particularly  those  in  or  near  the  part  affected.     If  you  can  move  a 
finger,  a  wrist,  an  elbow,  or  any  joint  affected,  in  the  least  without  pain, 
do  so,  and  continue  to  do  so  several  times  daily.     You  can  in  due  time 
make  the  affected  parts  move  more  and  more  freely.     You  must  practi- 
cally live  out  of  doors,  breathing  fresh  air  freely  and  constantly.     Your 
food  must  be  plain,  very  moderate  in  quantity,  and  thoroughly  chewed. 
These  are  important. 

Too  much  food,  and  improper  kinds,  particularly  meats,  and  lack  of 
exercise,  beyond  question,  are  the  chief  causes  of  the  condition  of  the 
body  that  allows  rheumatism  to  gain  a  foothold.  Exposure  to  damp- 
ness, sitting  on  the  ground,  getting  chilled  when  heated  from  exercise, 
—  these  may  be  the  immediate  inciting  causes,  and  they  should  always 
be  avoided,  but  there  is  an  unhealthful  condition  of  the  body  back  of 
them.  To  cure,  remove  this  unnatural  condition.  Unless  the  trouble 
has  gone  too  far,  and  the  joints  have  become  solid,  nature  will  remedy 
the  trouble  if  she  has  a  fair  chance.  Bathing  and  brushing  and  rubbing 
the  skin  are  important,  as  they  help  more  impurities  to  work  out  through 
that  channel.  And  do  not  forget  to  drink  freely,  all  you  have  the 
slightest  desire  for,  of  pure,  soft  water.  In  most  cases  it  requires  years 
of  improper  living  to  cause  the  condition  that  makes  rheumatism 
possible.  It  takes  months  and  perhaps  years  of  care  and  persistent 
effort  to  get  entirely  rid  of  it.  Most  of  those  who  have  suffered  with 
chronic  rheumatism  have  no  faith  in  the  power  of  medicine  to  effect 
a  permanent  cure.  Nature  must  do  it,  and  you  must  help  by  giving  her 
every  chance. 

The  great  trouble  in  effecting  a  cure  of  this  .disease  is  the  long  and 
persistent  effort  necessary.  Many  will  not  stick  to  it  long  enough.  But 
perseverance  with  the  treatment  described  will  bring  the  desired  result 
and  it  is  the  only  way  in  which  a  lasting  cure  can  be  made.  Medicines 
may  relieve  at  times,  but  there  is  something  wrong  in  the  way  of  living 
that  causes  rheumatism,  and  until  that  is  changed  there  can  be  no 
permanent  cure. 

4.  Water-drinking.  —  "  The  body  of  man  is  about  four  fifths  water. 
The  teeth,  the  hardest  and  densest  tissue  in  the  body,  contain  ten  per 
cent  of  water ;  the  bones  are  thirteen  per  cent  water,  the  muscles  are 


SOME   SPECIAL  REGULATIVE  PROCESSES  331 

three  quarters  water,  and  the  blood  four  fifths.  Gastric  juice  is  ninety- 
seven  per  cent,  sweat  is  ninety-eight  per  cent,  and  saliva  is  ninety-nine 
per  cent  water. 

All  the  vital  processes  are  carried  on  more  or  less  through  the  agency 
of  water.  Without  food  a  man  can  exist  for  sixty  days,  as  has  been 
demonstrated  by  experience.  But  six  or  eight  days  without  water  in 
some  form  means  a  horrible  death.  As  one  authority  expresses  it: 
"Water  is  a  very  important  food  element,  as  all  physiologic  changes 
take  place  in  a  watery  solution.  Water  is  the  medium  through  which 
the  body  is  nourished." 

It  must  always  be  remembered  that  the  water  excreted  from  the  body 
is  heavily  laden  with  various  poisonous  matters.  For  instance,  the  sweat 
contains  about  one  half  of  one  per  cent  of  urea,  besides  certain  lactates, 
sudorates,  and  inorganic  salts.  The  kidney  secretion  contains  nearly, 
two  per  cent  of  urea,  also  uric  acid,  creatin,  creatinin,  xanthin,  leucin, 
cystin,  taurin,  besides  many  other  poisons. 

Few  people  drink  enough  water.  Nine  out  of  ten  people  who  suffer 
from  chronic  constipation,  "  biliousness,"  habitual  headache,  kidney  dis- 
orders, etc.,  are,  in  reality,  merely  in  need  of  more  fluid,  with  which  the 
impurities  formed  in  their  bodies  may  be  washed  away.  One  week  of 
free  water-drinking  will  "cure  "  many  of  these  cases. 

Water  is  the  best  "cathartic"  —  the  only  safe  cathartic  —  known. 
The  cathartics  usually  given  act  by  causing  an  irritation  in  the  intes- 
tinal tube,  as  a  result  of  which  a  large  amount  of  water  is  drawn  from 
the  rest  of  the  body  to  the  intestine.  But  the  general  system  suffers 
for  the  fluid  thus  drained  off,  and  the  after  effect  is  to  leave  the  intestine 
in  a  worse  condition  than  in  the  beginning.  Only  by  another  dose  can 
the  fluid  be  drawn  back  into  the  intestine,  and  then  the  reaction  and 
resulting  constipation  are  more  marked  than  before.  So  with  repeti- 
tions the  matter  becomes  worse  and  worse.  As  all  practical  physicians 
know,  the  most  intractable  cases  of  constipation  are  those  resulting  from 
the  habit  of  taking  cathartic  drugs. 

In  disorders  of  the  kidneys,  water-drinking  is  quite  the  most  impor- 
tant feature  of  the  treatment.  The  kidneys  are  mainly  filters,  their 
function  being  mainly  to  separate  and  rid  the  body  of  a  certain  por- 
tion of  water  laden  with  impurities.  The  more  pure  water  taken  into 
the  system,  up  to  a  certain  point,  the  less  work  there  is  for  the  kidneys. 
There  need  be  no  fear  of  overtaxing  the  kidneys  by  free  drinking  of 
pure  water.  When,  however,  one  drinks  large  quantities  of  any  other 
fluid,  such  as  wine  or  beer,  the  work  of  the  kidneys  is  enormously 
increased.  In  fact,  it  is  safe  to  say  that  kidney  disease  always  follows 
the  excessive  use  of  beer. 


332  ELEMENTS   OF  PHYSIOLOGY 

For  one  unaccustomed  to  free  water-drinking  it  is  not  always  easy  to 
contract  the  habit.  Some  application  is  necessary.  The  following  is 
a  good  rule  for  general  usage :  On  rising,  two  tumblers  of  cold  water. 
Then  allow  half  an  hour's  interval  before  breakfast.  Two  hours  after 
breakfast,  and  until  within  a  half  hour  of  lunch  or  dinner,  three  tumblers 
of  water.  During  the  interval  between  two  hours  after  the  midday  meal 
and  one  half  hour  before  supper  or  dinner,  three  or  four  tumblers. 
During  the  time  between  two  hours  after  dinner  or  supper  until  bed- 
time, two  tumblers.  This  means  ten  tumblers,  or  about  two  quarts  per 
day;  and  this  is  as  little  as  any  one  can  afford  to  take." 

—  Adapted  from  W.  R.  C.  LATSON,  M.D. 

5.  Nature  alone  can  cure.  — This  is  the  highest  law  of  practical 
medicine.  .  .  .     Nature  creates  and  maintains ;  she  must  therefore  be 
able  to  cure.  — ROKITANSKY. 

6.  Appetites  given  away.  —  A  lady  once  asked  a  physician  where 
she  could  get  an  appetite.     "  Out  in  the  fresh  air,"  he  said ;  "just  go 
right  out  and  get  one.     Nature  has  thousands  of  appetites  to  give  away. 
The  winter  atmosphere  is  full  of  them.     All  that  Nature  asks  is  that 
you  come  after  them  yourself." 

7.  That  modern  clothing  is  ugly  and  inartistic,  that  it  is  destructive  of 
ease,  grace,  and  expressiveness,  that  it  produces  stiffness,  rigidity,  and 
awkwardness,  there  can  be  no  doubt. 

One  of  the  most  learned  and  famous  physicians  in  Europe  has  stated 
that  the  principal  cause  of  modern  disease  is  clothing.  A  cramped 
body  means  disease.  The  body  must  be  free  from  pressure.  Continu- 
ous pressure  anywhere  means  derangement  of  function.  The  worst 
feature  of  clothing  is  that  it  occasions  pressure  at  certain  critical  points, 
namely,  around  the  chest,  about  the  waist,  at  the  back  of  the  neck,  and 
about  the  limbs.  The  tightly-buttoned  coat  and  the  snug-fitting  dress 
make  natural  breathing  impossible.  The  ribs  are  drawn  inward  and 
downward,  the  breastbone  is  depressed,  and  the  beautiful  rotundity  of 
the  arched  chest  is  lost — usually  forever.  The  pressure  upon  the  back 
of  the  neck  from  a  shortened  coat-collar  causes  the  head  to  fall  forward 
and  affects  the  chest  in  the  same  manner. 

The  most  injurious  effect  of  the  corset  is  that  it  depresses  and  con- 
tracts the  chest,  and  thus  not  only  impedes  the  action  of  the  heart, 
lungs,  and  stomach,  but  causes  a  prolapse,  or  falling,  of  all  the  organs. 
Another  injurious  result  of  the  corset-wearing  is  that  it  interferes  with 
the  action  of  the  intestines  (peristalsis)  and  with  the  blood  circulation, 
thus  producing  constipation  and  various  inflammatory  conditions  and 
displacements  of  abdominal  and  pelvic  organs. 

The  pressure  of  a  tight  hatband  is  undoubtedly  the  principal  cause 


SOME   SPECIAL  REGULATIVE  PROCESSES  333 

of  baldness  among  men.  Women,  who  wear  hats  that  sit  lightly  upon 
the  head,  are  seldom  bald.  In  men  the  pressure  of  the  tight  hatband 
cuts  off  the  blood  supplying  the  roots  of  the  hair  with  nutriment,  and 
thus  causes  the  death  of  the  hair.  I  have  known  obstinate  chronic 
headache  to  disappear  promptly  upon  the  removal  of  a  tight  neck 
dressing.  These  high,  tight  neck  dressings  which  have  been  so  much 
the  fashion  recently  have,  in  many  cases,  completely  ruined  the  exquisite 
contour  of  the  neck. 

Another  evil  effect  of  modern  clothing  is  that  by  its  thickness,  it 
interferes  with  the  excreting  and  respiratory  action  of  the  skin.  The 
work  of  excretion  is  thus  either  thrown  upon  other  organs  already  over- 
taxed, or  upon  some  tissue  which  the  body  selects  as  a  possible  medium 
for  elimination.  Thus  it  is  likely  that  catarrh  is  always  caused  by  the 
inactivity  of  the  skin.  The  matter  thus  left  in  the  body  seeks  egress 
by  means  of  the  mucous  membrane,  which  is  merely  a  kind  of  internal 
skin,  and  so  we  have  catarrh.  —  Condensed  from  Health  Culture. 


CHAPTER  XVIII 
THE  SPECIAL  SENSES 

602.  In  the  special  senses  —  sight,  hearing,  smell,  taste, 
touch  (including  the  temperature  sense)  —  we  refer  the 
sensations  to  some  external  cause,  but  general  sensations 
(fatigue,  pain,  hunger),  as  previously  stated,  are  referred 
to  our  own  bodies.     You  learned  that  the  muscular  sense 
is  made  up  of  special  sensations  of  touch   and  general 
sensations  from  the  muscles.     Hence  the  much  discussed 
question  as  to  whether  the  muscular  sense  is  a  sixth  special 
sense,  is  best  answered  by  classing  it  with  the  general 
sense.     The  special  sense  of  touch  has  been  studied  in  a 
previous  chapter. 

603.  The  Sense  of  Taste  (Fig.  165).  — It  was  mentioned 
that  the  tip  of  the  tongue  has  a  very  keen  sense  of  touch. 
The  tongue  is  a  very  muscular  organ,  and  when  we  are  eat- 
ing, it  helps  to  keep  the  food  between  the  teeth  ;  it  also  does 
the  chief  part  of  the  work  in  the  beginning  of  the  process 
of  swallowing.     But  perhaps  its  most  important  function  is 
to  afford  a  home  for  the  nerves  of  taste.     These  nerves 
consist  of  a  branch  of  the  fifth  pair  of  nerves,  which  are 
distributed  over  the  front  part  of  the  tongue,  and  the  ninth 
pair,  which  go  to  the  back  part  of  the  tongue  (Fig.  201). 
Although  we  often  speak  of  food  as  being  palatable,  the 
sense  of  taste  in  the  palate  is  very  feebly  developed. 

604.  What  we  call  flavors  affect  us  through  the  sense 
of  smell.     If  the  nose  be  closed  with  the  hand,  a  piece  of 
onion  placed  on  the  tongue  does  not  have  the  "  taste  "  of 
onion  at  first,  nor  at  all,  unless  particles  are  wafted  up  and 

334 


THE  SPECIAL  SENSES  335 

pass  through  the  pharynx  into  the  nose.  An  apple  is,  un- 
der the  same  conditions,  as  tasteless  as  an  Irish  potato.  If 
the  nose  is  held  shut,  ground  coffee  placed  upon  the 
tongue  loses  its  flavor  and  is  as  tasteless  as  sand,  if  the 
tongue  is  wiped  dry.  The  way  to  make  these  tests  is 
to  obtain  the  articles  and  have  them  given  to  you  for  tast- 
ing without  knowing  which  you  are  getting;  then  find 
whether  or  not  you  can  tell  the  difference. 

Substances,  in  order  to  be  tasted,  must  first  be  dissolved 
on  the  tongue.  The  tip  of  the  tongue  is  most  sensitive 
to  sweets  and  salines,  the  back  part  to  bitters,  and  the  sides 
to  acids. 

605.  The  Sense  of  Smell  (Fig.  208). —  In  quiet  breathing 
most  of  the  air  passes  along  the  lower  parts  of  the  nasal 
passages,  just  above  the  hard  palate.     Fibers  of  the  olfac- 
tory nerve  end  mostly  in  the  higher  part  of  the  nasal 
passages.     When  we  wish  to  test  an  odor,  we  sniff,  that 
is,  we  take  a  sudden  inspiration  by  jerking  the  diaphragm 
down ;  a  volume  of  air  larger  than  usual  rushing  in,  more 
of  it  passes  over  the  parts  of  the   walls   in   which   the 
olfactory  fibers  are  located.     It  is  necessary  that  the  sub- 
stance producing  the   odor  be   in   a  very  finely  divided 
condition,  probably  gaseous. 

606.  Smell  has  its  source  in  the  beginnings  of  the  respir- 
atory passages,  just  as  taste,  is  at  the  gateway  of  the  ali- 
mentary canal ;  and  just  as  taste  by  its  influence  on  the 
salivary  and  gastric  glands,  greatly  influences  digestion,  so 
the  sense  of  smell  greatly  influences  the  respiratory  acts. 
The  breathing  of  a  pleasant  odor  increases  the  depth  of 
the  breathing.     Pleasant  odors,  as  of  flowers  and  of  fresh 
country  air  and  of  the  forest,  contribute  to  our  health  and 
well-being.     Why   do  foods  lose  flavor  when  one  has   a 
very  bad  cold  in  the  nose  ? 

SUBJECT  FOR  DEBATE.  Resolved,  That  Dr.  Oliver 
Wendell  Holmes's  assertion  is  false,  viz :  If  all  the  drugs 


ELEMENTS   OF  PHYSIOLOGY 

in  the  world  were  dumped  into  the  sea  it  would  be  a  great 
deal  better  for  mankind  —  and  a  great  deal  worse  for  the 
fishes. 

607.  THOUGHT  LESSON.     How  the  Body  shows  that  God 
is  Good.  — 

1.  Name  six  beneficent  natural  provisions  for  repair  of 
accidental  or  unusual  injuries  to  the  body. 

2.  State  six  facts   in   anatomy  showing  provisions  for 
protection. 

3.  State  six  similar  facts  in  physiology. 

4.  Name  four  anatomical  provisions  for  convenience  in 
use. 

5.  Name  four  devices  used  in  machinery,  examples  of 
which  occur  in  the  body. 

6.  Name   three   devices   of   architecture   found  in  the 
body. 

7.  Why   have   the   ears,    eyes,   nose,  and  mouth   been 
assigned  the  positions  relative  to  one  another  which  they 
occupy  in  the  head  ? 

SIGHT 

608.  By  the   use  of   the  senses  thus  far  studied,  we 
learn   almost   nothing   of   the   external   world   except   by 
actual  contact.     Sight  and  hearing  tell  us  of  objects  at 
a  distance.     Without  the  eye  the  body  is  comparatively 
helpless. 

609.  The  Orbit  (Fig.  51). — The  deep   bony  socket   in 
which  the  eye  rests  is  called  the  orbit.    Its  walls  are  formed 
by  inward  processes  of  the  frontal,  malar,  and  several  other 
bones.     There  is  an  opening  in  the  deepest  part  of  the 
socket  for  the  entrance  of  the  optic  and  oculo-motor  nerves, 
and  the  blood  vessels  that  supply  the  eye ;  the  deep  portion 
of  the  orbit  is  partly  occupied  by  a  cushion  of  fat  upon 
which  the  eyeball  rests,  and  which  yields  to  some  extent 
when  the  eye  is  struck. 


THE   SPECIAL   SENSES 


337 


610.  Oculo-motor  Muscles  (Fig.  213). — The  eyeball  is 
capable  of  being  turned  in  all  directions  by  means  of  six 
slender  muscles  which  begin  in  the  back  part  of  the  orbit. 
Four  of  them  are  straight.     The  one  above  turns  the  eye 
upward,  the  one  below  turns  it  downward,  the  one  toward 
the  nose  turns  it  inward,  and  the  one  toward  the  temple 
turns  it  outward.     The  other  two  are  oblique.     The  supe- 
rior oblique  muscle  passes  forward  through  a  loop  which 
serves     as     a     pulley 

near  the  inner  upper 
front  part  of  the  orbit 
(Fig.  213).  It  rotates 
the  eye  in  one  direc- 
tion, and  its  antagonist, 
the  inferior  oblique 
muscle,  rotates  it  in 
the  opposite  direction. 
"Cross  eyes"  are 
caused  by  too  great 
contraction  of  the  in- 
ternal straight  mus- 
cles, and  "wall  eyes" 
are  caused  by  too  great 
contraction  of  the  ex- 
ternal straight  muscles.  The  defects  may  be  remedied  by 
a  skillful  surgeon,  who  cuts  the  proper  muscle  with  a 
suitable  instrument,  and  permits  it  in  healing  to  become 
attached  to  another  point  farther  back. 

611,  A   person   is    blind   while   the   eyes   are   moving. 
Watch   while   some   one   in    front   of    the   class    tries   to 
move  the  eyes  gradually  and  uniformly  across  the  field 
of  vision.     Do  the  eyes  move  by  jumps  or  steadily?     The 
motions  of  the  lids  and  eyeball  give  the  expression  of  the 
eye.     The  eyeball  itself  has  hardly  more  expression  than 
a  glass  eye. 

z 


FIG.  213.  —  A,  the  Muscles  of  the  Right  Eyeball 
(viewed  from  above).  B,  the  Muscles  of  the 
Left  Eyeball  (viewed  from  the  outer  side) . 

S.R,  superior  rectus;  Inf.R,  inferior  rectus;  E.R, 
external  rectus;  S.Ob,  superior  oblique;  Inf. Ob, 
inferior  oblique;  //,  the  optic  nerves;  ch,  their 
crossing  or  chiasma;  ///,  the  third  cranial  nerve. 


33* 


ELEMENTS  OP  PHYSIOLOGY 


612.  The  Conjunctiva.  —  The  eye  is  apparently  set  in  a 
slit  in  the  skin  of  the  face,  but  this  is  not  really  the  case. 
The  skin  of  the  eyelids  turns  inward  over  their  edges  and 
becomes  a  thin,  transparent,  and  exceedingly  sensitive 
mucous  membrane,  called  the  conjunctiva.  It  is,  like 
other  mucous  membranes,  composed  of  epithelial  cells. 
The  conjunctiva  goes  back  under  the  lid  and  over  half 
the  eyeball  itself  to  the  other  lid,  so  that  the  eye  is  really 
behind  the  skin.  When  the  eye  is  directed  very  much 

to  one  side,  the  con- 
junctiva is  sometimes 
seen  lying  in  wrinkles. 
The  veins  which  we 
think  we  see  in  the 
white  wall  of  the  eye- 
ball when  the  eye  is 
"blood-shot"  are  usu- 
ally in  the  conjunc- 
tiva, which  is  so  trans- 
parent that  we  do  not 
easily  see  it  unless  its 
vessels  are  swollen. 

613.   The     Eyeball 

(Fig.  214)  is  a  globular  chamber  filled  with  transparent 
fluids.  By  studying  Fig.  214  you  will  see  that  its  wall 
is  made  of  three  layers,  or  coats.  The  sclerotic  coat  in 
the  "white  of  the  eye"  is  the  tough  white  outer  coat 
of  connective  tissue.  It  preserves  the  shape  of  the 
eye  and  serves  for  the  attachment  of  the  muscles.  This 
coat  is  pierced  in  only  one  place,  and  that  is  for  the 
entrance  of  the  optic  nerve.  It  is  continuous  over  the 
front  of  the  eye,  where  it  becomes  transparent,  and  is 
called  the  cornea.  You  can  see  the  cornea  bulging  out 
in  the  front  of  a  classmate's  eye  if  you  look  at  the  eye 
from  the  side.  The  middle  coat,  the  coat  just  within  the 


etinji 
horoid 
'erotic  coat 


FiG.  214.  —  The  Anatomy  of  the  Eye. 


THE  SPECIAL  SENSES  339 

sclerotic,  is  the  choroid.  It  consists  of  pigment  cells  and 
blood  vessels;  its  function  is  to  absorb  the  superfluous 
light  which  may  pass  through  the  retina,  or  third  and  inner- 
most coat.  This  light,  if  reflected  to  and  fro  within  the 
ball,  would  confuse  the  vision.  The  continuation  of  the 
choroid's  layer  of  pigment  in  front  is  the  iris,  which  may 
be  of  various  colors,  and  which,  besides  the  pigment,  con- 
tains muscular  fibers.  Unlike  the  sclerotic,  the  choroid  is 
not  continuous  in  front,  for  the  iris  is  provided  with  an 
opening  called  the//////.  The  retina  is  inside  the  choroid 
and  lines  the  chamber.  It  is  made  by  the  distribution  of 
the  hundred  thousand  or  more  fibers  of  the  optic  nerve. 
Just  behind  the  iris  is  the  crystalline  lens  whose  func- 
tion is  to  bring  the  rays  of  light  to  a  focus  on  the  retina. 
It  is  in  a  transparent  capsule  from  the  edges  of  which  mus- 
cular fibers  radiate  to  the  wall  of  the  eyeball.  The  lens 
divides  the  chamber  into  two  cavities.  The  small  front 
cavity,  between  it  and  the  cornea,  is  filled  with  the  watery 
fluid  called  aqueous  humor.  The  main  cavity  is  filled  with 
the  jelly  like  vitreous  humor.  A  ray  of  light  in  going  from 
the  outer  world  to  the  retina,  passes  through  four  parts 
of  the  eye.  Name  them.  This  does  not  count  the  pupil, 
which  is  simply  a  hole. 

614.  Use  of  the  Lens. — Take  a  lens  that  is  rounded 
outward  (convex)  on  both  sides,  such  as  a  hand  magnifier, 
or  even  a  strong  lens  from  an  old  per- 
son's spectacles.  Hold  this  up  on  the 
side  of  a  room  opposite  to  a  window 
and  catch  the  image  of  the  window  on  FIG.  215 -Refraction of 
a  white  card-board  held  back  of  the  Lisht- 

lens.      This  illustrates  how  the  image 
of  an  external  object  is  formed  by  the 

.     „.  ,  ,  ,f        of  light  rays. 

crystalline   lens   upon    the   retina.      If 

some  one  stands  up  in  the  window,  does  he  appear  in  the 

upper  or  lower  part  of  the  image  ?     If  he  moves  to  the 


340 


ELEMENTS  OF  PHYSIOLOGY 


right,  in  what  direction  does  his  image  move  ?  The 
reversals  are  explained  by  the  crossing  of  the  rays  of 
light  as  they  pass  through  the  lens.  If  two  lenses  of 
different  thickness  be  used,  it  will  be  found  that  the  card- 
board must  be  moved  closer  to  catch  the  image  from  the 
thicker  lens. 

615.   Accommodation  (Fig.  216).  —  Hold  a  pencil  or  finger 
in  line  with  some  object,  as  a  picture  on  the  wall.     When 


IRIS 


C.M. 


FlG.  216.  —  Diagram  to  illustrate  Accommodation. 
Sc,  sclerotic  ;  C.M . ,  ciliary  muscle ;  Sp.  I,  suspensory  ligament ;  C  /,  crystalline  lens. 

looking  at  the  finger,  the  picture  is  blurred  and  vice  versa. 
When  looking  up  from  a  book  that  we  are  reading,  to  a 
distant  object,  we  do  not  realize  that  any  change  in  the  eye 
is  necessary ;  but  the  lens  changes 
in  shape,  becoming  more  flattened 
for  the  more  distant  object,  and 
becoming  thicker  again  when  a 
near  object  is  looked  at,  thus 
always  bringing  the  rays  to  a  focus 


FIG.  217. 


Normal  Eye,  in  which  Parallel  Rays  , . 

of  Light  (A,  A)  focus  the  image  upon  the  retina  at  whatever  dis- 
tance the  object  may  be.     But  the 

power  fails  at  a  point  called  the  near  point,  about  four 
inches  from  the  eye  for  most  persons,  and  the  image 
becomes  indistinct.  The  change  in  shape  of  the  lens  is 


THE  SPECIAL   SENSES 


341 


called  accommodation ;  it  is  brought  about  by  means  of 
the  muscular  fibers  around  the  lens.  Straining  of  the 
muscles  is  required  for  looking  at  very  near  objects. 

616.  Defects  of  Vision.  —  In  near-sighted  eyes  (Fig.  218) 
the  eye  is  too  long  from  front  to  back,  and  the  rays  come 
to  a  focus  before  reaching  the  retina.  Among  savage  na- 
tions, where  no  books  are  used,  almost  every  one  has  good 
sight,  and  nearsightedness  is  hardly  known.  Nearsighted- 
ness  may  be  inherited  or  may  begin  with  children  at  school. 
Some  children  seem  to  have  a  natural  wish  to  get  their 
eyes  close  to  the  book  or  writing.  This  is  the  very  worst 


FIG.  218. 

Myopic,  or  Nearsighted,  Eye,  in 
which  Parallel  Rays  of  Light 
(A", A"}  focus  the  Image  in  Front 
of  the  Retina  at  C' ,  producing  a 
Blurred  Image  on  the  Retina  at 
Bff,  the  Rays  diverging  from  C1. 


FIG.  219. 

Hypermetropic,  or  Farsighted,  Eye,  in 
which  Parallel  Rays  of  Light  (A't 
Af)  are  focused  behind  the  Retina 
at  C,  producing  a  Blurred  Image 
at  B>. 


thing  for  nearsightedness.  The  head  should  be  held  erect 
in  reading,  to  prevent  the  blood  congesting  in  the  eyes, 
and  to  prevent  round  shoulders  and  flat  chest.  The  proper 
distance  for  reading  is  fourteen  to  eighteen  inches.  The  far- 
sightedness (Fig.  2 1 9)  that  occurs  in  youth  is  caused  by  the 
eyeball  being  too  flat.  In  the  farsightedness  of  old  age  the 
lens  has  also  lost  its  elasticity,  so  that  its  shape  cannot  be 
sufficiently  changed  to  bring  the  lights  from  near  objects 
to  a  focus  on  the  retina.  In  farsightedness,  convex  glasses 
are  used,  and  in  nearsightedness,  concave  glasses  are  used. 
Astigmatism  is  a  defect  caused  by  unequal  curvature  of  the 
cornea  in  different  directions  (Fig.  220). 

617.   Regulation  by  Iris  of  Amount  of  Light  admitted. 
—  Look  toward  a   bright   window   or   the   sky  and   note 


342  ELEMENTS   OF  PHYSIOLOGY 

by  means  of  a  hand  mirror  the  size  of  the  pupil.  Turn  at 
right  angles  to  the  light,  still  looking  in  the  mirror,  and 
note  the  size  of  the  pupils.  What  have  you  noticed  about 

the  eyes  of  a  cat  at  night  or  in  a 
darkened  room  ?  How  do  your 
own  eyes  feel  when  going  from 
the  dark  into  a  lighted  room  ? 
Can  you  see  as  well  when  you 
first  go  from  a  brightly  lighted 
room  into  a  dim  lighted  one,  as  af- 
ter being  in  the  dim  light  for  a 
short  time  ?  The  iris  contains  cir- 
cular muscle  fibers,  which  reduce 

FIG.  220. -Test  for  Astigmatism.    the    size    Qf    the   pupil>    and   mdi_ 

If  this  defect  exists,  the  lines  that  run        ,  •  /-••  1-1  i 

in   a  certain   direction   will   appear     atmg     fibers,      which     enlarge     the 

d7rSionsthan  the  Hnes  in  °ther  PUP*1'     The  arrangement  of  pig- 
ment sometimes  follows  the  line 
of  the  fibers.     Have  you  ever  noticed  lines  in  the  iris  ? 

618.  After-images.  —  Did  you  ever  whirl  a  stick  with  a 
glowing  coal  on  its  end  ?    What  was  noticed  ?     Can  you 
notice  anything  similar   if   you  shake   the  hand  up  and 
down  quickly  before  the  face  ?     If  you  gaze  for  a  moment 
at  a  bright  light,  then  quickly  close  the  eyes,  what  is  noticed 
after  the  eyes  are  closed  ?     These  effects  are  produced  by 
the  bleaching  action  of  light  upon  the  pigment  of  the  retina, 
an  effect  which  persists  for  a  fraction  of  a  second  after  the 
light  is  removed. 

619.  The  Yellow  Spot,  or  center  for  most  distinct  vision 
(especially  for  color),  is  near  the  middle  of  the  back  part 
of  the  retina  (Fig.  214). 

620.  Blind  Spot.  —  Light  falling  on  the  optic  nerve  itself 
does  not  give  the  sensation  of  light,  but  gives  it  only  when 
falling  upon  the   ends   of   the   nerve  fibers.     Where  the 
optic  nerve  enters  the  eyeball,  there  are  none  of  these  end- 
ings, and  the  light  that  falls  there  does  not  enable  us  to 


THE   SPECIAL   SENSES  343 

see  anything.     In  the  following  experiment  shut  the  right 
eye,  and  be  careful  not  to  let  the  eye  waver:  — 

*  Read  this  line  slowly.     Can  you  see  the  star  all  the  time  ? 

If  not,  change  the  distance  to  the  book  and  read  the  line 
again.  In  the  human  eye  the  optic  nerve  enters  not  in  the 
center,  but  at  a  point  toward  the  other  eye.  Although  the 
optic  nerve  along  its  course  is  not  sensible  to  light,  yet  if  it 
be  cut,  it  does  not  give  pain,  but  gives  the  sensation  of  a 
flash  of  light. 

621,  THOUGHT  LESSON.  The  Eye. — (In  writing  out 
this  lesson,  underline  the  words  you  supply.) 

1.  The  eye  is  shielded  from  blows  by  bony  projections  of 
, ,  and . 

2.  The  hairs  of  the  eyebrows  lie  inclined  toward in 

order  to  turn from  the . 

3.  The  eyelashes  are  to  keep  out and .     I  find 

by  trying  it  that  I  [can  or  cannot]  see  the  position  of  a 
window  with  my  eyes  closed. 

4.  The  tears  are  to .     We  wink  in  order  to  carry 

the over  the ,  also  in  order  to and  to . 

5.  The  front  of  the  eyeball  looked  at  from  the  side  is 

seen  to  be .     It  is   called  the  cornea.     The  colored 

portion  of  the  eye,  the  iris,  is  to the  amount  of . 

6.  The  hole  in  the  iris,   occupied   by   the   transparent 

aqueous  humor  is  called  the .     It  is  for  the  purpose 

of . 

7.  It  appears  to  be  black  because  no is from 

the   interior  wall  of   the    eye.     I    know   that   the   iris   is 
partly  muscle,  because  it the  size  of  the . 

8.  By  holding  my  finger  in  line  with  writing  on  the  black- 
board, I  find  that  I   [can  or  cannot]  see  both  finger  and 
writing  distinctly  at  one  time.     This  is  because  in  order  to 

focus  the upon  the ,  the must  change  shape 

for  every  change  in  the  distance  of  the  object  looked  at. 


344  ELEMENTS   OF  PHYSIOLOGY 

622.  Care  of  the  Eyes.  —  Sight  is  Priceless.  (When 
reading  is  mentioned  in  these  suggestions,  it  is  meant 
to  include  such  work  as  writing,  sewing,  embroidering, 
etc.) 

1.  The  light  should  be  steady,  not  flickering ;  we  should 
not  read  after  sunset  by  the  fading  twilight ;  we  should  not 
read  with  the  sunlight  falling  on  the  book;  we  should 
not  read  facing  a  window  or  with  a  light  directly  in  front, 
unless  the  eyes  are  protected  by  a  shade.     The  lamp  should 
also  be  shaded.     Incandescent  electric  lights  give  an  uneven 
light,  because  of  the  shadow  cast  by  the  filament;  a  shade 
diffuses  its  light  more  evenly  and  protects  from  the  glare. 
Light  curtains  diffuse  the  light  evenly,  but  dark  curtains 
cause  lights  and  shadows. 

2.  The  state  of  the  eyes  is  of  importance :   We  should 
not  read  when  tired  or  sleepy;  when  convalescing  from 
an  illness;   with   the  head  bent  down;  or  heated  by  the 
burner ;  when   the   eyes   are   sore ;  when  they  are  tired, 
unless   we   rest   them   every   few   minutes  by  looking  at 
far   objects ;    when   riding   in  jolting  cars  and  carriages ; 
when  the  circulation  is  impeded  by  tight  clothing  around 
the  neck. 

"  Tobacco  blindness  "  sometimes  results  from  smoking. 
The  first  symptom  is  color  blindness,  which  is  followed  by 
haziness  of  vision,  and  finally,  by  partial  or  complete  loss 
of  sight. 

3.  The   kind  of  work    is    of    importance :    The    type 
from   which    books   are    printed   should    be   large.      The 
paper  should   not  be  pure  white  or   glazed,  but  a  neu- 
tral tint;   it  should  be  opaque,  so  that  the  printing  will 
not    show    through    from    the    reverse    page :    the    lines 
should  not  be  more  than  four   and  a  half  inches  long. 
Publishers  of  magazines  are  the  worst  offenders  in  using 
shiny  glazed   paper  because  it  brings  out  the  beauty  of 
fine  engravings. 


THE   SPECIAL   SENSES 


345 


FIG.  221. 

A  Front  View  of  the  Left  Eye,  with 
the  Eyelids  partially  dissected 
to  show  Lachrymal  Gland,  L.  G., 
and  Lachrymal  Duct,  L.D.t  to 
Nose. 


623.  The  Tear  Gland  is  located  above  the  eyeball,  be- 
tween the  ball  and  the  bony  arch  on  the  side  toward  the 
temple.  It  is  flattened  and  oval  in  shape,  about  three  quar- 
ters of  an  inch  in  length.  About  ten  small  ducts  lead  from 
it  and  open  on  the  under  side  of  the 
upper  lid.  The  secretion  that  it  fur- 
nishes to  the  conjunctiva  is  formed 
continually.  The  tears  pass  across 
the  eye  and  flow  into  two  small  ducts, 
the  openings  into  which  can  be  seen 
on  the  borders  of  each  eyelid  near 
the  inner  angle  of  the  eye.  They 
lead  to  a  canal  which  empties  into 
the  nasal  passage  (Fig.  166).  When 
one  weeps,  why  is  it  necessary  to 
blow  the  nose  frequently  ?  At  the  ordinary  rate  of  sup- 
ply, the  tears  do  not  overflow,  as  there  is  a  waxy  secretion 
along  the  edge  of  the  eyelid  that  turns  them  toward  the 
ducts.  When  have  you  noticed  a  waxy 
secretion  in  the  corner  of  the  eye  ? 

624.   The  Need  of  Two  Eyes.  — We 
judge  the  distance  of  objects  by  the 
lines  of  convergence  of  the  two  eyes. 
A  boy  with  one  eye  has  difficulty  in 
knowing   when    a    ball    thrown   will 
reach  his  hand.     When   we  look   at 
FIG.  222.-Diagram  of  a  a  solid  object,  each  eye  sees  a  little 
stereoscope.  more  of  the  object  on  its  side  than 

Two  photographs,  A  and  5,  are    doCS  the  Other.        Thus  tWO  CVCS  make 
seen  combined  at  C.    The  rays  * 

of  light  from  A  and  B  are  re-  it  easier  to  distinguish  solid  bodies. 

fracted  by  the  prisms  into  the     ._  .   . 

eyes  so  that  they  appear  to     By  taking  tWO  photographs  Of  3.  SCQUQ 

from    slightly   different    points     and 

arranging  them  so  that  the  eyes  look  at  the  pictures 
separately  at  the  same  time,  the  idea  of  solidity  is  given. 
The  stereoscope  (Fig.  222)  secures  this  arrangement. 


346 


ELEMENTS   OF  PHYSIOLOGY 


625.  Cooperation  of  Eye  and  Touch.  —  The  infant  reaches 
for  the  moon.  It  is  learning  by  reaching  for  things  seen  to 
judge  of  distance.  By  feeling  of 
things  seen  it  soon  learns  to  tell 
round  things  from  flat  things  by 
sight  alone.  The  aid  that  touch  gives 
to  the  sense  of  sight  is  illustrated  by 
the  case  of  a  boy  who  had  been  blind 
from  birth  and  received  sight  at  the 
age  of  twelve  years  by  means  of  a  sur- 
gical operation.  At  first  he  could  not 
distinguish  a  globe  from  a  circular 
card  until  he  had  touched  them. 
He  had  become  acquainted  with  dogs 
and  cats  by  feeling  but  did  not  know 


FIG.  223.  —  Diagram 
Course  of  the  Retinal  Nerve 
Fibers. 


of  the   them  apart  by  sight  alone.    One  day 


Light  from  A  strikes  the  outer  part 


he  picked  up  the  cat  and  .recognized 
for  the  first  time  the  connection  be- 
tween the  new  sense  of  sight  and  the 
these  parts  go  to  the  right  half  oi^  familiar  one  of  touch.     On  put- 

of  the  brain,  B.     A/  represents 

the  nose.  The  spots  A  and  A   ting  the  cat  down  he  said,  "  So,  puss, 
I  shall  know  you  next  time." 

HEARING 


on    the    retinae    are    habitually 
stimulated  together. 


626.  The  ear  may  be  described  in  three  parts,  the  outer, 
middle,  and  inner  ear  (Fig.  224).  The  outer  ear  consists 
of  the  cartilaginous  concha,  the  part  that  is  usually  spoken 
of  as  the  "  ear,"  and  the  meatus,  the  canal  leading  into  the 
head  from  the  lower  part  of  the  concha.  Which  part  of 
the  concha  is  not  cartilaginous  but  fatty  tissue  ?  Part  of 
the  wall  of  the  meatus  is  of  cartilage,  but  the  deeper  part 
has  a  wall  of  bone.  The  entrance  to  the  meatus  is  guarded 
by  hairs,  and  its  wall  is  covered  with  a  bitter  wax  secreted 
by  glands  in  the  lining.  Its  inner  end  is  closed  by  the 
tympanic  membrane,  which  is  sometimes  called  the  driim, 


THE   SPECIAL   SENSES 


347 


but  it  is  only  a  drum  skin.  Three  little  bones  stretch  across 
the  true  drum,  which  is  the  middle  ear,  to  a  small  film 
separating  the  middle  ear  from  the  internal  ear.  These 
three  little  bones  are  called  the  hammer,  anvil >  and  stir- 
rup. The  middle  ear  communicates 
with  the  pharynx  by  a  narrow  tube 
called  the  Eustachian  tiibe.  This 
tube  is  for  the  purpose  of  admit- 
ting air  to  the  middle  ear,  so  as  to 
equalize  the  air  pressure  on  each 
side  of  the  membrane  and  prevent 
straining  it.  Sometimes  blowing 
the  nose  may  press  the  air  up  into 
the  middle  ear  and  press  the  walls  FIG.  224.  —  Diagram  of  Left  Ear. 
of  the  Eustachian  tube  together  and  close  it.  This  causes 
slight  deafness  for  the  time.  The  pressure  may  be  relieved 
by  holding  the  nose  closed  and  swal- 
lowing, thus  opening  the  passage  to 
the  middle  ear.  One  end  of  the 
hammer  is  attached  to  the  inner  sur- 
face of  the  drum  skin  ;  the  other  end 
is  attached  to  the  anvil ;  and  one 
prong  of  the  anvil  is  attached  to  the 
stirrup,  which  in.  turn  is  fastened  by 
base  to  the  small  film  stretched 
across  a  round  hole  in  the  bone,  open- 
ing into  the  inner  ear,  or  labyrinth. 
The  inner  ear  consists  of  several 
cavities  containing  a  liquid  in  which 
rest  the  endings  of  the  auditory  nerve.  The  cavities  are 
the  snail-shell  and  the  three  loops,  or  semicircular  canals. 
627.  Sound  waves,  entering  by  the  meatus,  set  the  drum 
skin  to  shaking ;  the  vibrations  are  conveyed  by  the 
chain  of  bones  across  the  middle  ear  to  the  liquid  of  the 
inner  ear.  The  wave  travels  through  air  in  the  outer  ear, 


FIG.  225.  —  Bones  of  Right 
Ear,  enlarged. 

c,  hammer;  d,  anvil;  e,ft 
stirrup. 


348  ELEMENTS   OF  PHYSIOLOGY 

solids  in  the  middle  ear,  and  liquids  in  the  inner  ear.     The 
vibrations  of  the  liquid  start  nerve  impulses  in  the  fibers 
of  the  auditory  nerve,  and  when  these  impulses  are  re- 
ceived and  interpreted  in  the  brain, 
the  miracle  of  the   conversion   of 
the  external  sound  wave  into  the 
sensation  of  sound  is  complete. 

628.    The  Equilibrium  Sense. — 
It  is  now  believed  that  the  semi- 
circular  canals  of   the   inner    ear 
FIG.  226.  —  The  inner  Ear,  or  are  not  concerned  in  hearing.  The 
Labyrinth.  weight  of  the  liquid  they  contain 

gt  vestibule;  /",  snail  shell;  k,  semi-  •  .-i  ^-i 

circular  canals.  pressing      Upon      the      HQVVQ      fibers 

located   in   them    and   exerting    a 

varying  pressure  according  to  the  position  of  the  body, 
gives  us  the  "equilibrium  sense,"  which  enables  us  to  know 
the  position  of  the  body  at  all  times,  that  we  may  preserve 
its  equilibrium.  Sight  and  the  muscular  sense  also  prob- 
ably contribute  to  maintain  the  equilibrium. 

629.  Care  of  the  Ear.  —  The  meatus  is  self-cleansing ; 
the  wax  changes   into  dry   scales,   which   fall  out.     The 
external  ear  should  be  washed,  but  when  we  reach  the 
passage,  we  should  go  no  deeper  than  we  can  easily  reach 
with  the  tip  of  the  finger  covered  with  a  damp  cloth  ;  espe- 
cially the  finger  should  not  be  forced  into  the  tender  ears 
of  children.     A  blow  with  the  flat  hand  upon  the  ear  may 
force  the  air  in  and  injure  the  tympanum.     Picking  the  ear 
with  hard  or  sharp  objects  is  dangerous  to  the  tympanum. 

630.  Sometimes    the  wax  collects  in  a  lump  near  the 
drum,  causing  deafness.     The  remedy  is  to   syringe   the 
meatus  with   warm   water  until  the  lump  is  softened  and 
comes   away.     The    bitter   wax   is    a    protection    against 
insects.     Quinine  often  does  great  damage  to  the  hearing. 
Chronic  cold  in  the  throat  reaching  the  ear  through  the 
Eustachian  tube  sometimes  injures  the  hearing. 


THE  SPECIAL   SENSES 


349 


THE  VOICE 

631.  The  larynx,  in  which  the  voice  originates,  is  a 
cartilaginous  box  with  three  sides,  the  sharpest  corner 
forming  a  ridge  in  front  (Fig.  227). 
In  many  persons  the  larynx  is  promi- 
nent in  the  neck,  and  is  called  the 
Adams  apple.  The  lid  of  the  voice- 
box,  or  larynx,  is  also  of  cartilage,  and 
is  called  the  epiglottis.  Across  the 
middle  of  the  box  are  stretched  two 
bands,  or  half-curtains,  called  the  vocal 
cords  (Fig.  228).  Their  ends  are  at- 
tached to  the  front  and  back  of  the 
larynx.  They  are  not  true  cords,  how- 
ever, as  they  are  thin  and  flat,  and  one 

edge  of  each 
band  is  at- 
tached to  the 
side  of  the 
larynx.  Since 

the  cords  run  across  the  middle 
of  the  chamber  from  front  to 
back,  the  free  edges  are  brought 
near  together.  The  slit,  or  open- 
ing between  these  edges,  is  called 
the  glottis.  During  ordinary 
respiration  the  cords  are  relaxed 

Larynx  above  the  Vocal  Cords,      and    the    slit    is   wide    Open.       To 
with  the  Mucous  Membrane  re-  i        j_i  *.\.  i  j 

moved  make  the  voice  the  vocal  cords 

showing  right  vocal  cord;  left  vocal     must  be  brought  very  near  to- 

cord:  cartilages  to  which  the  vocal  ,  •,  -,       -,  ,  •     •,   ,  j 

cords  are  attached  behind;  front    gether  and   drawn  tight,   and  a 
edge  of  the  larynx.  current    of    air  must   be  forced 

through  the  narrow  slit  and  throw  the  cords  into  vibration. 

The  front  ends  of  the  cords  are  attached  to  the  larynx  just 


4 


FIG.  227. 

View  of  the  lett  side  of  the 
larynx;  i,  front  portion 
of  hyoid  bone;  2,  upper 
edge  of  larynx;  3,  lower 
portion  of  larynx ;  4, 
second  ring  of  trachea. 


FIG.  228.  —  Cross-section   of  the 


350 


ELEMENTS   OF  PHYSIOLOGY 


within  the  angle,  or  ridge,  called  the  Adam's  apple.  The 
rear  ends  are  attached  to  two  little  movable  cartilages  at 
the  back  of  the  chamber.  The  moving  of  these  little  car- 
tilages by  the  muscles  of  the  larynx  brings  the  edges 
together  and  tightens  the  cords. 

632.  Sound  Waves,  or  sound  vibrations,  are  imparted  to 
the  air  by  the  tremulous  motion  of  the  cords.  The  limits 
of  the  vibrations  which  the  human  voice  is  capable  of  mak- 
ing are  from  42  vibrations  per  second  for  the  lowest  tone, 
to  over  2000  vibrations  per  second  for  the  highest  tone. 


FlG.  229.  —  The  Shape  of  the  Mouth  in  sounding  the  Vowels  a,  e,  oo. 

Lower  C  of  the  soprano  is  produced  by  256  vibrations  per 
second.  The  limits  of  vibrations  which  the  human  ear  is 
capable  of  hearing  are  from  16  to  50,000  vibrations  per 
second,  but  until  they  reach  a  rate  of  about  50,  the  sound 
is  more  like  a  buzz  than  a  tone.  Some  people  cannot 
hear  the  voice  of  mice,  or  the  squeak  of  a  bat,  because  of 
the  high  pitch  being  beyond  the  limit  of  their  hearing. 

633.  THOUGHT  LESSON.  How  the  Voice  may  vary.  - 
The  rate  of  vibration  of  a  cord,  and  hence  the  pitch  of  a 
sound,  are  influenced  in  several  ways.  Is  the  string  of 
a  violin  or  of  a  guitar  tuned  up  or  down  by  tightening  it  ? 
Which  is  higher  in  pitch,  a  long  or  a  short  string  of  a  harp 
or  a  piano  ?  Which  makes  a  higher  note,  the  light  or  the 
heavy  string  of  a  violin  or  a  guitar?  The  pitch  of  the 


THE  SPECIAL   SENSES  351 

note  given  by  a  string  may  be  raised  in  three  ways  :  tight- 
ening, shortening,  or  decreasing  the  weight  of  the  string. 
From  these  facts  explain  why  the  voice  rises  in  pitch  when 
we  are  excited,  the  muscles  at  that  time  being  contracted 
with  greater  force.  Why  does  a  cold  with  congestion  of 
the  cords  cause  a  person  to  speak  in  a  hoarse,  deep  voice  ? 
Why  does  a  man,  whose  larynx  is  larger  than  a  woman's, 


FIG.  230.  FIG.  231.  FIG.  232. 

A,  Resonance  Cavity  of  the  Nose;  B,  Resonance  Cavity  of  the  Mouth;  C,  Resonance  Cavity 
of  the  Pharynx;  D,  Soft  Palate;  E,  Tongue;  F,  Point  at  which  Vibration  begins. 

Fig.  230  shows  soft  palate  (Z>)  in  normal  position,  allowing  air  in  naso  pharynx  to  vibrate 
in  unison  with  initial  note.  Fig.  231  shows  soft  palate  raised,  shutting  off  this  resonance 
and  rendering  tone  thin  and  hard.  Fig.  232  shows  another  common  fault.  The  tongue  is 
lowered,  increasing  the  size  of  the  mouth  cavity.  This  increases  the  volume  of  the  tone  but 
renders  the  quality  harsh  and  hollow.  (Latson.) 

have  the  deeper  voice  ?  Why  does  a  boy's  voice  change  as 
his  larynx  enlarges  ? 

A  man's  voice  has  usually  a  pitch  of  one  octave  below 
that  of  a  woman  or  a  boy.  The  range  of  the  human  voice 
is  about  two  octaves.  The  voice  may  also  vary  in  — 

634.  Volume,  or  loudness,  as  well  as  in  pitch.  How  do 
we  speak  loudly  at  one  time  and  softly  at  another  ?  If  a  tin 
pan  is  struck  gently,  the  sound  is  weak  ;  if  it  is  struck  with 
force,  the  sound  is  louder.  We  make  the  voice  louder  by 
stronger  expiration  of  the  breath,  thus  sending  the  air 
with  more  strength  against  the  tightened  vocal  cords. 


352  ELEMENTS   OF  PHYSIOLOGY 

Two  persons  sing  a  song  together  in  the  same  pitch  and 
with  the  same  loudness;  yet  you  can  readily  distinguish 
a  difference  in  the  two  voices.  This  is  because  of  a  dif- 
ference in  — 

Quality,  which  is  the  third  variation  possible  in  a  voice. 
Sound  in  wind  instruments  is  strengthened  by  resonance, 
which  is  a  kind  of  instantaneous  echo  in  the  pipes. 

635.  The  vibration  of  the  vocal  cords  alone  produces  a 
weak,  squeaky  sound,  but  their  vibrations  are  reenforced  or 
strengthened  by  the  vibration  of  the  walls  of  the  lungs  and 
windpipe  below,  and  of  the  nose  and  mouth  above.     These 
echoes,  combining  with  and  reenforcing  the  vibration  of 
the  cords,  determine  the  quality  of  the  voice.     Just  as  the 
shape  and  material  of  the  walls  of  the  violin  give  the  quality 
to  its  tone,  so  the  shape  and  condition  of  the  nasal  passages, 
throat,  etc.,  give  characteristic  quality  to  each  human  voice. 
If  the  nasal  passages  are  stopped  up  by  catarrh,  the  per- 
son is  said  to  speak  in  a  nasal  tone,  or  through  the  nose, 
but  a  "nasal"  tone  really  results  only  when  the  sound 
cannot   come  through  the  nose.      Such  a  person's  voice 
does  not  change  its  quality,  when  he  speaks  with  his  nose 
stopped  with  his  fingers.     But  a  voice  which  has  correct 
nasal  resonance  will  change  its  quality  when  the  nose  is  held. 
Try  it,  and  see  whether  your  voice  retains  its  nasal  reso- 
nance.     Let  one  pupil  read  aloud  at  the  back  of  the  room 
where  the  others  do  not  see  him,  and  find  whether  they 
can  tell,  by  the  change  in  his  voice,  at  which  word  he 
closes  his  nose  in  the  midst  of  the  reading.      The  vocal 
cords  are  not  used  at  all  in  whispering.      It  is   akin   to 
whistling. 

636.  Duration  of  Sound.  —  In  singing,  single  sounds  are 
more  or  less  prolonged.      In  speech,  the  principal  changes 
are  in  the  duration  of  the  sound,  and  in  the  resonance  in 
the  mouth.     In  whispering,  audible  breathing  is  cut  off  by 
the   tongue  and  lips,   and  words  are  articulated,  although 


THE   SPECIAL   SENSES  353 

no  sound  comes  from  the  vocal  cords.  A  public  speaker 
ordinarily  utters  125  words  per  minute.  If  there  are  four 
sounds  to  a  word,  this  amounts  to  500  sounds  each  minute 
or  eight  each  second. 

637.  Is  the  Voice  a  Stringed  or  a  Wind  Instrument  ?  - 
The  inappropriate  names  of  the  vocal  cords  may  lead  a 
student  incorrectly  to  suppose  that  the  voice  is  a  stringed 
instrument.     It  is  a  wind  instrument ;  the  vocal  bands  cor- 
respond to  the  vibrating  edge  in  the  opening  in  an  organ 
pipe,  the  throat  and  air  passages  correspond  to  the  pipe, 
and  the  lungs  correspond  to  the  bellows  that  furnish  the 
current  of  air. 

638.  Alcohol  and  Tobacco.  —  Smokers  are  frequent  suf- 
ferers from  affections  of  the  throat.     Smoking  may  produce 
a  constant  " hacking"   cough.    The  hot,  poisonous  smoke, 
to  say  nothing  of  the  poisonous  vapor  of  nicotine,  brought 
in  contact  with  the  vocal  cords,  is  almost  certain  to  pro- 
duce mischief.     Singers  and  public  speakers  usually  have 
to  give  up  the  use  of  tobacco  on  this  account.      Cigarette 
smoking  is  especially  bad  for  the  voice,  as  the  smoke  is  in- 
haled.    The  deep-toned  voice  of  the  chronic  drinker  may  be 
an  indication  of  inflammation  of  the  larynx,  a  disease  from 
which  beer  drinkers  often  suffer. 

639.  Care  of  the  Voice.  —  The  voice  should  not  be  used 
more    than    is   absolutely    necessary   when    it   is    hoarse. 
Catarrh  may  injure  the  voice  by  injury  to  the  vocal  cords 
or  by  obstruction  of  the  nasal  passages. 

640.  The  best  way  for  a  child  to  acquire  distinct  and 
refined  speech,  is  to  hear  it  habitually.     The  number  of 
people  that  are  allowed  to  grow  up  handicapped  by  hasty, 
harsh,   indistinct,   or   disagreeable   speech,   is   very  great. 
Parents  and   teachers   should   remember  as  children  are 
growing  up,  what   an  advantage   to  them  in  after  life  a 
refined,  melodious  voice  will  be.     Nearly  all  children  have 
sweet  voices  when  young,  but  many  lose  them  before  adult 

2  A 


354  ELEMENTS   OF  PHYSIOLOGY 

life  on  account  of  acquired  nervous  habits,  dusty  and  ill- 
ventilated  rooms,  deformity  of  lungs  due  to  restrictive 
clothing,  or  from  singing  during  the  time  their  voices 
are  changing  or  attempting  tunes  beyond  the  compass  of 
their  voices. 

641.  Culture  of  Voice.  —  Voice  culture  is  often  more  of 
a  straining  than  a  training.     Its  mechanical  nature  is  re- 
vealed by  the  term  "  voice  building  "  (whatever  that  may 
mean)  used  by  some  singing  teachers.     The  pupil  is  taught 
to  raise  the  soft  palate  and  depress  the  larynx,  etc.  (see 
Figs.  230,  232).     Rigidity  of  the  muscles  of  chest,  neck,  jaw, 
and  larynx  results  and  self-consciousness  assumes  charge. 

When  the  singer  does  not  listen"  too  closely  to  his  own 
voice,  the  muscles  are  more  likely  to  be  free  from  rigidity. 
Muscles  in  this  condition  are  perfectly  dominated  by  the 
mental  state ;  this  applies  to  both  tone  and  gesture.  Breath- 
ing exercises  which  call  for  a  rigid,  over-filled  chest  destroy 
this  flexibility. 

CONCLUSION 

642.  Thus  we  see  with  reference  to  the  care  of  the  voice, 
as  with  taking  care  of  the  health  in  general,  that  overcare 
and  too  much  effort  have  an  effect  opposite  to  that  in- 
tended.    We  must  trust  largely  to  the  natural  tendencies  of 
our  wonderful  organisms  toward  sound  health  and  perfec- 
tion of  function.    If  we  exert  great  effort  and  attempt  very 
much  interference,  we  are  likely,  in  our  ignorance,  to  do 
more  harm  than  good.    We  do  not  even  know  what  life  is. 
When  we  say  that  life  consists  of  activity  of  the  cells,  we 
are  simply  stating  the  limitations  of  science.     The  power 
which  causes  this  birth,  growth,  and  destruction  of  cells 
is  beyond  our  comprehension.     We  know  nothing  of  the 
mechanism  occurring  in  the  protoplasm  of  the  cells.     All 
that  the  wisest  can  say  is :  — 

"  In  Nature's  infinite  book  of  secrecy 
A  little  can  I  read.1' 


APPENDIX 


EMERGENCIES 

Cuts.  —  There  is  danger  of  bleeding  to  death  if  an  artery  of  any  size 
is  cut.  Stop  the  flow  of  blood  immediately  by  compressing  the  artery 
with  the  finger,  between  the  wound  and  the  heart.  Next  twist  a  hand- 


FIG.  233 

The  method  of  applying  the  knotted 
handkerchief,  to  compress  a  divided 
artery.  A,  B,  track  of  the  inner 
artery  of  the  left  arm. 


FIG.  234. 

A,  C,  the  track  of  the  left  femoral 
artery;  the  compress  applied  near 
the  groin. 


kerchief  and  tie  a  hard  knot  in  the  middle.  Place  the  knot  over  the 
artery  and  carry  the  ends  around  the  limb  and  tie  it  loosely.  Place 
a  stick  under  the  handkerchief  and  twist  until  the  fingers  can  be 
removed  from  the  compression  without  return 
of  the  bleeding  (see  Figs.  233  and  234). 

Sprains.  —  See  Chapter  VI,  §  124. 

Broken  Bones.  —  See  Chapter  VI,  §  122.  A 
convenient  bandage  may  be  made  out  of  a  piece 
of  calico  one  yard  square,  by  cutting  it  across 
from  one  corner  to  another  (Fig.  235).  For 
method  of  using  bandage  as  a  support  for  a 
broken  arm,  see  Fig.  236. 

355 


FIG.  235. 


356 


APPENDIX 


To  prevent  Mouth-breathing,  bands  may  be  arranged  as  shown  in 
Fig.  237.  Dr.  Tafts,  of  Pittsburg,  gets  good  results  by  sticking  a  strip 
of  court  plaster  across  the  closed  lips. 

Burns.  —  If  the  clothes  catch  fire,  do  not  run,  as  this  only  fans  the 
flames,  but  wrap  quickly  around  the  body  a  coat,  rug,  shawl,  blanket,  or 

other  woolen  article.  The 
skirts  of  girls  are  a  source 
of  danger  when  they  stand 


FIG.  236. 


FIG.  237. 


near  a  fire  in  an  open  fireplace  without  a  fender,  or  by  a  fire  out  of 
doors.  Life  has  sometimes  been  saved  by  throwing  the  victim  to  the 
ground,  and  then  putting  sand  or  dirt  on  the  burning  clothes. 


FIG.  238.  —  Resuscitation:   Inspiration.     (Brinckley.) 

In  Cases  of  Drowning  the  first  thing  to  be  done  is  to  remove  the 
water  from  the  throat  and  lungs  by  holding  the  person  up  by  the 
waist,  with  the  face  downward.  Then  draw  the  tongue  forward  and 


EMERGENCIES  357 

keep  it  in  place  by  tying  with  the  middle  of  a  handkerchief  or  band,  so 
that  it  may  not  fall  back  and  close  the  throat  ;  the  ends  of  the  band 
should  cross  under  the  chin  and  be  tied  around  the  neck.  Next  pro- 
ceed to  restore  by  artificial  breathing  according  to  the  method  shown 
in  Figs.  238  and  239.  The  teacher  should  illustrate  the  method  of 
fastening  the  tongue,  the  pupil  holding  a  short  stick  between  the  teeth 
to  represent  the  tongue.  The  teacher  should  then  work  the  arms  of 


FIG.  239.  —  Resuscitation:  Expiration.    (Brinckley.) 

the  pupil  to  show  inspiration  and  expiration  in  artificial  breathing.  The 
boy  need  not  lie  down  but  should  stand  where  the  class  may  see  him. 

Artificial  Breathing  (Sylvester's  Method),  applicable  to  asphyxia 
from  fire,  gas,  electric  shock,  or  drowning.  A  coat  or  cushion  should 
be  placed  under  the  shoulders  to  serve  as  a  support.  First  Step  (Fig. 
238)  :  The  arms  should  be  raised  above  the  head  with  force  in  order  to 
raise  the  ribs.  Second  Step  (Fig.  239)  :  The  arms  should  be  lowered 
and  pressed  against  the  sides  so  as  to  compress  the  chest.  Repeat  these 
movements  about  fifteen  times  each  minute,  continuing  for  an  hour  or 
several  hours  until  natural  breathing  is  restored. 

Snake  Bites. — Very  few  snakes  are  poisonous.  The  four  snakes 
of  the  United  States  that  are  virulently  poisonous  are  the  rattlesnake 
(diamond  rattler  and  common  rattler),  ground  rattlesnake  (has  no 
rattles V  moccasin,  and  copperhead.  The  last-named  is  the  most  dan- 
gerous. The  copperhead  is  of  a  golden  brown  color,  with  dark  V-shaped 
blotches  meeting  on  the  back.  All  venomous  snakes  have  broad  tri- 
angular heads  and  short  tails.  Their  b'ite  is  known  from  the  marks  left 
by  the  two  fangs.  Other  snakes  do  not  have  fangs.  The  wound  made 
by  a  venomous  snake  should  be  immediately  sucked.  The  blood  should 
be  confined  to  the  bitten  member  (see  Figs.  233,  234).  Potassium 
permanganate  and  peroxide  of  hydrogen  are  valuable  remedies.  They 
should  be  used  only  under  direction  of  a  physician. 


358 


APPENDIX 


Poisons 

Opium 
Morphine 
Codeine 
Laudanum 
Paregoric 
Soothing  sirup 
Dover's  powder 

Carbolic  Acid 
Creosote 


Arsenic 
Rough  on  rats 
Paris  green 
White  arsenic 


Phosphorus 
Rat  poison 
Matches 

Belladonna 

Deadly  nightshade 
Atropin 

Concentrated  Acids 
Sulphuric  (vitriol) 
Muriatic 
Nitric 
Oxalic 

Alkalies 
Lye 

Caustic  potash 
Soda 
Ammonia 


POISONS   AND   ANTIDOTES 

Symptoms  Treatment  and  Antidotes 


Drowsiness ;  stupor ;  con- 
tracted pupils ;  slow  breath- 
ing; perspiration  profuse 


Severe  pain;  odor  of  the 
acid ;  mucous  membrane 
white ;  skin  clammy 


Cause  vomiting 'or  use  stomach 
tube;  keep  patient  awake 
by  vigorous  walking  and 
other  means;  dash  cold 
water  on  face  and  chest; 
give  strong  coffee  freely 


Do  not  cause  vomiting ;  give 
milk,  or  flour  and  water, 
white  of  eggs 


Intense  pain  in  abdomen;  Cause  vomiting  repeatedly; 
thirst;  vomiting;  skin  cold  give  hydrated  oxide  of  iron 
and  clammy  with  magnesia  (druggist), 

then  strong  salt  water 


Vomiting;  pain  in  stomach ; 
purging 


Enlarged  pupils ;  eyes  bright; 
mouth  and  throat  dry 


Feeling  of  burning  in  mouth, 
throat,  and  stomach ;  blis- 
ters on  lips ;  vomiting  and 
weakness 


Burning  sensation;  pain  in 
stomach;  vomiting;  diffi- 
culty in  swallowing;  skin 
cold ;  pulse  weak 


Cause  vomiting ;  give  strong 
soap  suds.magnesia  in  water 


Cause  free  vomiting 


Do  not  cause  vomiting ;  give 
baking  soda,  4  teaspoonfuls 
to  a  glass  of  water ;  chalk ; 
soap ;  lime ;  magnesia 


Do  not  cause  vomiting ;  give 
olive  oil ;  thick  cream ; 
melted  butter  and  vaseline ; 
vinegar ;  lemon  juice 


NOTE.  —  In  those  cases  of  poisoning  where  vomiting  is  necessary,  it  may  be  in- 
duced by  a  drink  of  warm  water,  or  powdered  alum  in  a  little  molasses,  or  a 
mixture  of  ground  mustard  in  warm  water.  The  vomiting  should  be  repeated 
until  the  stomach  is  thoroughly  washed  out. 


INDEX 


The  meaning  of  each  technical  word  is  fully  explained  in  the  text  when  the  word  is  first  used. 
This  explanation  can  be  found  by  using  the  first  reference  given.  The  numbers  below 
refer  to  pages. 


Absorption,  207. 

by  stomach,  213,  221. 
Acid,  54. 

Air,  composition  of,  159. 
Albino,  2. 
Albumen,  28,  53. 
Albumin,  28,  52,  192. 
Alcohol,  255,  257,  14. 
and  gout,  43. 
effect  on  — 

energy  of  body,  323,  324. 

heart,  113. 

liver,  230. 

lungs,  169,  170. 

nerves,  292. 

nervous  system,  314,  315,  316. 

nutrition,  42. 

protoplasm,  42. 

red  corpuscles,  113. 

skin,  14. 

stomach,  204,  279. 

temperature,  258. 

voice,  353. 

white  corpuscles,  113. 
Is  it  a  food  ?  204,  256,  257. 
Alimentary  canal,  205. 
Alkali,  54. 
Alkaloids,  188. 
Ameba,  30,  281. 

taking  food,  31. 
Anatomy,  25. 
Antidotes,  358. 
Antiseptics,  187. 
Antitoxin,  183. 
Appetite,  237,  262,  332. 
Aseptic,  187. 
Asphyxia,  357. 
Astigmatism,  342. 
Atlas,  62. 
Auricle,  87. 


Automatic  action,  303. 

Axis,  62. 

Axis  cylinder,  or  axon,  285. 


Bacillus,  178. 
Bacteria,  178. 

destroyed  in  body,  182. 
out  of  body,  186. 

effects  of,  181. 

place  in  nature,  177,  179. 

their  work  in  the  body,  179. 
Balancing  organ,  348. 
Bandage,  355. 
Baseball,  141. 
Baths,  ii. 

kinds  of,  22. 

rules  for,  23. 
Biceps,  125,  128. 
Bicuspid  valve,  90. 
Bicycling,  141. 
Bile,  217. 
Biology,  25. 
Bleeding,  114,  355. 
Blind  spot  of  eye,  342. 
Blister,  u. 
Blood,  circulation  of,  86. 

control  of  flow,  97,  98. 

function  and  composition,  82. 

plasma,  83,  86. 

rate  of  flow,  96. 

red  corpuscles,  58,  83,  84. 

white  corpuscles,  84,  182. 
Blood  vessels  and  heart,  88. 

nervous  control,  97. 

structure  of,  92. 
Bone,  alcohol  and,  79. 

cells,  40. 

composition  of,  71. 

deformities  of,  75,  76. 

359 


36o 


INDEX 


Bone  {continued) 

growth  of,  41. 

names  of,  57. 

nourishment  of,  74,  78. 

number  of,  59. 

of  head,  58,  60. 

red  marrow,  58. 

shapes  of,  56,  68. 

structure,  40,  70. 
Boxing,  141. 
Brain,  300. 

coverings  of,  300. 

parts  of,  301. 

weight  of,  301. 
Breathing,  see  Respiration. 
Broken  bone,  74,  79,  355. 
Bronchial  tubes,  150. 
Bronchus,  150. 
Burns,  356. 

Caecum,  222. 
Canaliculi,  40. 
Capillaries,  89. 

structure  of,  92. 
Capsule  of  joint,  69. 
Carbohydrates,  53,  193. 
Carbon  dioxid,  51,  160. 
Carbon  monoxid,  172. 
Carpus,  65. 
Cells,  26,  29,  i,  2,  4. 

ciliated,  151. 

community  of,  31. 

division  of,  31. 

epithelial,  35. 

life  of,  30,  41,  116. 

of  bone,  40. 

of  cartilage,  38. 

of  connective  tissue,  34. 

of  fat,  35. 

of  muscle,  121. 

of  nerves,  46. 

parts  of,  29. 
Cellulose,  53,  249. 
Cerebellum,  301. 

functions  of,  307. 
Cerebro-spinal  system,  296. 
Cerebrum,  301. 

functions  of,  304,  307,  309. 
Cervical,  61. 
Chyme,  213. 
Cilia,  151. 
Circulation  of  blood,  82,  88. 

hygiene  of,  109. 
Cleanliness,  five  degrees  in,  174. 


Clothing,  22,  191,  231,  262,  332. 

and  climate,  22. 

materials  of,  22. 
Coagulation,  85. 
Coccyx,  61. 

Coffee-drinking,  14,  272. 
Cold,  taking  a,  6,  no,  329. 
Colon,  222. 

Complexion,  19,  20,  24. 
Compositions  or  essays,  subjects  for,  162, 

280,  316. 
Condyles,  59. 

Consumption,  176,  180,  190,  191. 
Cooking,  239,  240,  242,  244,  246,  247, 248, 

254- 

Cranial  nerves,  303,  304. 
Cuts,  355. 

Dancing,  141. 
Dandruff,  5. 
Debates,  177,  262,  335. 
Dendron,  284. 
Dermis,  i. 

organs  of,  5. 
Dextrin,  220. 

Diaphragm  (di'-a-fram),  154. 
Diastole  (di-as'-to-le),  87. 
Dieting,  203. 
Digestion,  analysis  of,  220. 

hygiene  of,  236. 

outline  of,  198. 
Dislocation,  70,  75. 
Division  of  labor,  32. 
Dorsal,  61. 
Drowning,  356. 

Drugs,  14,  43,  179,  188,  237,  250,  280,  328. 
Duodenum,  216. 

Ear,  structure  of,  346. 

care  of,  348. 
Emergencies,  355. 
Emulsion,  53,  218. 
Endothelium,  92. 
Enteroptosis,  231. 
Epidermis,  i. 

growth  of,  4. 
Epiglottis,  208,  349. 
Equilibrium  sense,  348. 
Esophagus,  209. 
Essays,  see  Compositions. 
Excretion,  13. 
Exercise,  benefits  of,  137,  142,  144. 

dangers  of,  143. 


INDEX 


361 


Exercise  (continued) 

effect  on  growth,  146. 

forms  of,  141,  144. 

mind  and,  145. 
Expiration,  148,  156. 
Eye,  338. 

care  of,  344. 

defects  of,  341. 

structure  of,  339. 


Fatigue,  312,  323. 

Fats,  53, 194. 

Femur,  66. 

Ferment,  206. 

Fermentation,  178,  179,  255. 

Fever,  326. 

Fibers,  29. 

Fibrin,  85. 

Fibula,  61. 

Flavors,  335. 

Follicle,  7. 

and  work,  200. 

composition  of,  243. 

function  of,  45. 

ratios,  201. 

sources  of,  197. 
Food,  and  climate,  53,  323. 
Food  substances,  52. 
Freckles,  2. 
Fruits,  243,  244. 
Function,  i. 


Ganglion,  286. 
Gastric  glands,  212. 
Gastric  juice,  212. 
Germicide,  187. 
Germs,  see  Bacteria. 
Girdle,  of  pelvis,  66. 

of  shoulder,  65. 
Gland,  12. 
Glottis,  349. 
Glycogen,  288. 
Gout,  79,  no,  327. 


Hair,  7,  n. 
Haversian  canal,  40. 
Headache,  266,  313,  314. 
Hearing,  346. 
Hemorrhage,  114. 
Hepatic  artery,  227. 
Hepatic  vein,  227,  228. 


Hygiene,  defined,  26. 

in  disease,  325-333. 

of  circulation,  109-118. 

of  digestion,  236-267. 

of  muscles,  137-146. 

of  nervous  system,  309-319. 

of  respiration,  162-192. 

of  sight,  344. 

of  skeleton,  74-81. 

of  skin,  11-24. 

temperance,  268-281. 
Hyoid  bone,  60. 
Hypnotism,  316. 

Indigestion,  215,  327. 
Infectious  diseases,  182. 
Innominate,  66. 
Inorganic,  25. 
Inspiration,  148,  155. 
Intestinal  juice,  217,  219. 
Intestine,  large,  see  Colon. 
Intestine,  small,  216. 
Iron,  54. 

Joint,  68. 

kinds  of,  70,  71. 
of  arm,  79. 
parts  of,  69. 

Kidneys,  234. 

Lachrymal  bone,  60. 
Lachrymal  duct,  345. 
Lacteal,  218. 
Lacunae,  40. 
Larynx,  149,  349. 
Leather,  2,  35. 
Lens,  crystalline,  339. 
Levers,  126,  144. 
Ligament,  69. 
Lime,  54. 
Liver,  222,  223. 

a  digestive  gland,  223. 

a  guardian,  224. 

anatomy  of,  226,  227. 

a  storeroom,  228. 
Lobule  of  lungs,  150. 
Lumbar,  61. 
Lungs,  aid  to  heart,  103. 

alcohol  and,  169. 

anatomy  of,  148,  150. 

nature  of,  147. 


362 


INDEX 


Lymph,  105. 

relation  to  blood,  105. 

why  it  flows,  107. 
Lymphatic  glands,  108. 
Lymphatics,  106. 
Lymphatic  spaces,  104. 
Lymphatic  system,  104. 

necessity  for,  105. 


Malar  bones,  60. 
Malaria,  183. 
Mammals,  241. 
Massage,  103. 
Matrix,  38. 
Maxillary  bone,  60. 
Membrane,  30. 
Metacarpus,  65. 
Metatarsus,  67. 
Microbes,  see  Bacteria. 
Mineral  foods,  52,  54,  194. 
Molds,  177. 
Mole,  10. 
Mosquito,  184. 
Mouth,  205. 

Mucous  membrane,  6,  12. 
Muscles,  118. 

attachment  of,  124. 

cells  of,  119. 

contraction  of,  46,  120. 

intercostal,  155. 

kinds  of,  119. 

names  and  positions,  127,  139. 

nervous  control  of,  132. 

structure  of,  120,  122,  124. 

tissue  of,  45. 

tone  of,  136. 
Muscular  sense,  291,  334. 


Nails,  9. 
Narcotic,  14. 
Nerve,  285. 

center,  286. 

coordination,  283. 

motor,  49,  287,  291. 

sensory,  49,  287. 

structure  of,  48,  285. 

tissue,  46. 
Neuroglia,  286. 
Neuron,  285. 
Nucleolus,  29. 
Nucleus,  29. 
Nuts,  244. 


Oil  gland,  7. 
Opium,  42,  188,  280. 
Organ,  i,  33. 
Organic,  25. 
Organism,  44. 
Osmosis,  222. 
Overstudy,  175. 
Oxidation,  44,  51. 


Pain,  290,  325. 

Palate  bones,  60. 

Pancreas,  217. 

Papilla,  3,  7,  10. 

Paralysis,  308. 

Patella,  67. 

Pelvis,  66. 

Pepsin,  213. 

Periosteum,  39. 

Peristalsis,  210. 

Peritoneum,  211. 

Perspiration,  6,  n. 

Phalanges,  65,  67. 

Pharynx,  149,  207. 

Phrenology,  316. 

Physician,  43,  74,  115,  142,  188,  280,  357. 

Physiology,  25. 

Pigment,  2. 

Plants,  how  different  from  animals,  28, 

50. 

Pleura,  152. 
Poisons,  358. 
Pore,  5. 

Portal  vein,  222,  226. 
Process  on  bone,  62. 
Proteid,  52,  54,  193,  200. 

test  for,  196. 
Protoplasm,  27. 

how  known,  28. 
Proud  flesh,  n. 
Ptomaines,  181. 
Pylorus,  214. 


Rectum,  223. 
Reflex  action,  294,  308. 
Renal  artery,  234. 
Respiration,  147. 

artificial,  356. 

ease  in,  158. 

hygiene  of,  163. 

modifications  of,  159. 

muscles  of,  165. 
Resuscitation,  356,  357. 


INDEX 


363 


Retina,  63. 
Rheumatism,  330. 
Ribs,  63. 
Running,  141,  164. 


Sacrum,  61. 
Saliva,  206. 
Salivary  glands,  206. 
Salt,  54. 
Scars,  55. 
Secretion,  13. 
Semilunar  valve,  88. 
Sensation,  special,  288. 

general,  288. 
Serous  membrane,  12. 

cavity,  12. 
Serum,  85. 
Shoes,  75,  122. 
Sight,  336. 

Sigmoid  flexure,  223. 
Sitting,  75. 
Skeleton,  arrangement  of,  59. 

functions,  56. 

hygiene  of,  74. 
Skin,  i. 

care  of,  20. 

functions  of,  21. 
Skull,  59. 
Sleep,  112,  309. 
Smell,  335. 
Snake  bites,  357. 
Spinal  bulb,  50,  98,  302. 
Spinal  column,  61,  73. 
Spinal  cord,  292. 
Spleen,  109. 
Sprain,  75. 

Standing,  positions  in,  78. 
Starch,  53,  193. 

test  for,  196. 
Stomach,  210. 
Substances  of  the  body,  53. 
Sugar,  53,  193. 

forms  of,  219. 
Sweat  glands,  5,  6. 
Sweeping,  163. 

Sympathetic  system,  109,  296. 
Synovial  fluid,  69. 
System,  i. 
Systole  (sys'-to-le) ,  87. 


Tarsus,  67. 
Taste,  334. 


Teeth,  care  of,  19. 

milk  teeth,  17. 

number  and  names,  15. 

structure  of,  17. 
Temperature,  of  body,  22,  320. 

of  house,  in. 

perception  of,  290. 
Tendon,  125. 
Thoracic  duct,  106. 
Thorax,  63. 
Tibia,  67. 
Tissues,  i,  33. 

bony,  39. 

cartilaginous, 

connective,  34. 

epithelial,  36,  37,  92. 

fatty,  35. 

master,  33. 

muscular,  45. 

nervous,  46. 

supporting,  33,  34. 

tabulated,  41. 

Tobacco,  effect  on  skin,  14. 
on  growth,  79. 
on  heart,  114,  115. 
on  lungs,  170. 
on  throat,  209. 
on  voice,  353. 

instinct  against,  160. 
Tonsils,  209. 
Touch,  289. 
Touch  corpuscles,  287. 
Toxin,  181. 
Trachea,  149. 
Turbinated  bones,  60. 
Typhoid  fever,  182. 


Urea,  21,  133,  229,  234,  247. 
Ureter,  234. 


Vaccination,  185. 
Vagus  nerve,  99. 
Vasomotor  nerves,  97,  98. 
Vegetarian,  244,  251. 
Veins,  88,  102. 
Ventilation,  of  schools,  171. 

of  churches,  170. 

methods  of,  173. 

mistakes  in,  174. 
Ventricle,  87. 
Vermiform  appendix,  222. 
Vertebra,  61,  73. 


364 


INDEX 


Villi,  216. 

Voice,  care  of,  354. 

pitch,  350. 

quality,  352. 

tobacco  and,  353. 

volume,  351. 
Vomer  bone,  60. 


Waist  measure,  232. 
Wart,  to. 


Waste  products,  133,  198,  225,  229. 

how  measured,  199. 
Water,  22,  52,  238,  330. 
Wrestling,  141. 
Wrinkles,  7. 

Xanthin,  188. 


Yeast,  178,  179,  255. 
Yellow  spot  of  eye,  342. 


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Chemistry,  Meteorology,  Zoology,  Botany,  The  Human  Body,  The  Races  of  Man- 
kind. Each  chapter  is  a  very  brief  and  very  clear  treatise,  complete  so  far  as  it 
goes,  which  emphasizes  the  methods  of  the  subject  in  hand,  and  illustrates  them 
by  constant  reference  to  practical  things.  Many  simple  experiments  are  suggested, 
nearly  all  of  which  the  child  will  wish  to  try.  Particular  stress  is  laid  on  matters 
that  form  part  of  a  child's  daily  life.  His  daily  experiences  are  explained,  so  that, 
for  example,  the  essential  principles  of  the  telephone,  the  dynamo,  will  be  under- 
stood. The  twentieth-century  child  rides  to  school,  it  may  be,  on  an  electric  car. 
He  ought  not  to  regard  an  electric  motor  as  a  mysterious  piece  of  benevolent 
magic.  There  should  be  some  one  to  explain  to  him  what  it  is  and  why  it  does  its 
work.  This  volume  performs  the  office.  It  answers  the  questions  that  every  boy 
asks  and  stimulates  an  intelligent  curiosity.  Its  illustrations  have  been  chosen 
from  the  best  sources  and  each  one  is  accompanied  by  a  very  full  title.  Merely  to 
turn  to  the  cuts  and  to  read  their  titles  constitutes  a  tolerably  complete  elementary 
course  of  instruction.  The  author  of  the  book,  is  a  teacher  of  experience,  having 
been  successively  Instructor  at  the  U.  S.  Military  Academy  at  West  Point,  Professor 
in  the  University  of  Wisconsin,  President  of  the  University  of  California,  and 
Director  of  the  Lick  Observatory. 


Tarr  and  McMurry  Geographies — Supplementary  Volume 

TEXAS 

By  B.   G.   LITTLBJOHN,   A.M. 

PRINCIPAL  WEST  BROADWAY  SCHOOL,  GALVESTON,  TEXAS 
Illustrated        Cloth       35  cents  net 

Containing  chapters  on  the  Physiography  of  the  State,  Agricultural  Industries, 
Ranching,  Fisheries,  Railroads,  Manufacturing,  Mineral  Resources,  Political 
Divisions,  Government,  Education,  and  History. 


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